The information in this preliminary prospectus supplement is not complete and may be changed. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell nor do they seek an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

We are offering 15,000,000 shares of our common stock, par value $0.01 per share.

Our common stock is listed on the New York Stock Exchange, or NYSE, under the symbol "SM." On August 5, 2016, the last reported trading price of our common stock as reported on the NYSE was $29.30 per share.

Investing in our common stock involves risks. See "Risk Factors" beginning on page S-14 of this prospectus supplement and on page 4 of the accompanying prospectus.

We have granted the underwriters a 30-day option to purchase up to an additional 2,250,000 shares from us, at the public offering price, less the underwriting discount.

Neither the Securities and Exchange Commission ("SEC") nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The underwriters expect to deliver the shares of our common stock to purchasers on or about , 2016.

This document is in two parts. The first part is the prospectus supplement, which describes the specific terms of this offering and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference into the accompanying prospectus. The second part is the accompanying prospectus, which gives more general information about securities we may offer from time to time, some of which may not apply to this offering. Generally, when we refer to this prospectus, we are referring to both this prospectus supplement and the accompanying prospectus. Before you invest in our common stock or this offering, you should carefully read this prospectus supplement and the accompanying prospectus, in addition to the information contained in the documents we refer to under the heading "Where You Can Find More Information" and "Incorporation by Reference" in this prospectus supplement.

You should rely only on the information contained in or incorporated by reference in this prospectus supplement, the accompanying prospectus and any free writing prospectus we may provide you in connection with this offering. If any information varies between this prospectus supplement, the accompanying prospectus or documents incorporated by reference herein prior to the date of this prospectus supplement, you should rely on the information in this prospectus supplement. We have not, and the underwriters have not, authorized any other person to provide you with additional or different information. If anyone provides you with additional, different or inconsistent information, you should not rely on it. We are not, and the underwriters are not, making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted.

The information contained in this prospectus supplement and the accompanying prospectus or in any document incorporated by reference herein or therein is accurate and complete only as of the date hereof or thereof, respectively, regardless of the time of delivery of this prospectus supplement and the accompanying prospectus or of any sale of our common stock by us or the underwriters. Our business, financial condition, results of operations and prospects may have changed since those dates.

Unless the context otherwise indicates, the terms "SM Energy," "the Company," "we," "us" and "our" in this prospectus supplement mean SM Energy Company, a Delaware corporation, and its subsidiaries. Certain oil and natural gas industry terms used in this prospectus supplement are defined in the "Glossary of Oil and Natural Gas Terms" beginning on page S-37 of this prospectus supplement.

We are subject to the informational requirements of the Securities Exchange Act of 1934, as amended (the "Securities Exchange Act"), and we file annual, quarterly and other reports and other information with the Securities and Exchange Commission (the "SEC"). You may read and copy any document we file with the SEC at the SEC's public reference room at 100 F Street NE, Washington, D.C. 20549-2521. Please call 1-800-732-0330 for further information concerning the operation of the public reference room. Our SEC filings are also available on the SEC's web site at http://www.sec.gov. Unless specifically listed under "Incorporation by Reference" below, the information contained on the SEC web site is not intended to be incorporated by reference in this prospectus supplement and you should not consider that information a part of this prospectus supplement.

We make available free of charge on or through our Internet website, http://www.sm-energy.com, our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Securities Exchange Act as soon as reasonably practicable after we electronically file such material with, or furnish it to, the SEC. In addition, information contained on our Internet website is not part of this prospectus supplement and does not constitute a part of this prospectus supplement.

We "incorporate by reference" in this prospectus supplement certain documents that we have previously filed with the SEC. This means that we are disclosing important information to you without actually including that information in this prospectus supplement by referring you to other documents that we have filed separately with the SEC. The information incorporated by reference is an important part of this prospectus supplement. Information that we later provide to the SEC, and which is deemed "filed" with the SEC, will automatically update information that we previously filed with the SEC, and may replace information in this prospectus supplement and information that we previously filed with the SEC. We incorporate by reference the following documents in this prospectus supplement, which you should review in connection with this prospectus supplement:

We also incorporate by reference each of the documents that we file with the SEC (excluding those filings made under Items 2.02 or 7.01 of Form 8-K or other information furnished to the SEC) under Sections 13(a), 13(c), 14, or 15(d) of the Securities Exchange Act on or after the date of this prospectus supplement and before the termination of the offering of common stock under this prospectus supplement shall be deemed to be incorporated in this prospectus supplement by reference and to be a part hereof from the date of the filing of such documents. Any statements made in such documents will automatically update and supersede the information contained in this prospectus supplement, and any statements made in this prospectus supplement update and supersede the information contained in past SEC filings incorporated by reference into this prospectus supplement.

We will provide, at no cost to you, a copy of all documents incorporated by reference into this prospectus supplement to each person, including any beneficial owner, to whom we deliver this prospectus supplement, upon written or oral request. You may request a copy of these filings by writing or telephoning us at the following address or telephone number:

Investor Relations
SM Energy Company
1775 Sherman Street, Suite 1200
Denver, Colorado 80203
(303) 861-8140
information@sm-energy.com

This prospectus supplement contains "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933, as amended (the "Securities Act") and Section 21E of the Securities Exchange Act. All statements, other than statements of historical facts, included in this prospectus supplement that address activities, events, or developments with respect to our financial condition, results of operations, or economic performance that we expect, believe, or anticipate will or

may occur in the future, or that address plans and objectives of management for future operations, are forward-looking statements. The words "anticipate," "assume," "believe," "budget," "estimate," "expect," "forecast," "intend," "plan," "project," "will," and similar expressions are intended to identify forward-looking statements. Forward-looking statements appear throughout this prospectus supplement, and include statements about such matters as:

Our forward-looking statements are based on assumptions and analyses made by us in light of our experience and our perception of historical trends, current conditions, expected future developments, and other factors that we believe are appropriate under the circumstances. These statements are subject to a number of known and unknown risks and uncertainties, which may cause our actual results and performance to be materially different from any future results or performance expressed or implied by the forward-looking statements. Some of these risks are described in the Risk Factors section in Part I, Item 1A of our 2015 Form 10-K, and include such factors as:

We caution you that forward-looking statements are not guarantees of future performance and actual results or performance may be materially different from those expressed or implied in the forward-looking statements. The forward-looking statements in this prospectus supplement speak as of the filing date of this prospectus supplement. Although we may from time to time voluntarily update our prior forward-looking statements, we disclaim any commitment to do so except as required by securities laws.

PROSPECTUS SUPPLEMENT SUMMARY

This prospectus supplement summary highlights information contained elsewhere in this prospectus supplement, the accompanying prospectus, and the documents we incorporate by reference. It does not contain all of the information that you should consider before making an investment decision. For a more complete understanding of our business and this offering, you should carefully read the entire prospectus supplement, the accompanying prospectus and the documents incorporated by reference herein, including our historical financial statements and the notes thereto, which are incorporated herein by reference from our 2015 Form 10-K and our Quarterly Reports on Form 10-Q for the periods ended March 31, 2016 and June 30, 2016. You should read "Risk Factors" beginning on page S-14 of this prospectus supplement, on page 4 of the accompanying prospectus and Item 1A. "Risk Factors" in our 2015 Form 10-K and Quarterly Reports on Form 10-Q for the periods ended March 31, 2016 and June 30, 2016, for more information about important risks that you should consider before making a decision to invest in our common stock.

Certain information with respect to our estimated proved reserves referred to and incorporated by reference herein is based in part upon the audit of our proved reserve estimates by Ryder Scott Company, L.P., a firm of independent petroleum engineers. Such information is included and incorporated herein in reliance on the authority of such firm as an expert in petroleum engineering.

SM Energy Company

We are an independent energy company engaged in the acquisition, exploration, development, and production of oil, natural gas, and NGLs in onshore North America. Our core assets and active development positions are located in the Eagle Ford shale in south Texas, the Bakken/Three Forks in North Dakota and the Permian Basin in west Texas. We also have a delineation and exploration program in the Powder River Basin in Wyoming.

Our strategic objective is to profitably build our ownership and operatorship of North American oil, natural gas, and NGL producing assets that have high operating margins and significant opportunities for additional economic investment. We pursue growth opportunities through both exploration and acquisitions, and we seek to maximize the value of our assets through industry leading technology application and outstanding operational execution. We focus on achieving high full-cycle economic returns on our investments and maintaining a simple, strong balance sheet through a conservative approach to leverage.

As of year-end 2015, our proved reserves were 471.3 MMBoe. In the second quarter of 2016, production averaged 157,200 Boe per day. As of the end of the second quarter of 2016, our leasehold acreage totaled approximately 390,000 net acres in the Eagle Ford shale in south Texas, the Bakken/Three Forks in North Dakota and the Permian Basin in west Texas, approximately 171,000 net acres in the Powder River Basin and 477,000 net acres in other areas, of which 79,000 acres we recently announced were subject to contracts for sale.

Corporate Information

We were founded in 1908 and incorporated in Delaware in 1915. Our initial public offering of common stock was in December 1992. Our common stock trades on the New York Stock Exchange under the ticker symbol "SM." Our principal offices are located at 1775 Sherman Street, Suite 1200, Denver, Colorado 80203, and our telephone number is (303) 861-8140. Our website address is www.sm-energy.com; information included or referred to on our website is not part of this prospectus supplement.

Recent Developments

Pending Acquisition

On August 8, 2016, we entered into a definitive membership interest purchase agreement (the "Purchase Agreement") with Rock Oil Holdings LLC (the "Seller") to acquire (the "Acquisition") 100% of the membership interests in JPM EOC Opal, LLC (the "Target"), a Delaware limited liability company and wholly-owned subsidiary of Seller, which owns undeveloped leasehold interests, producing wells and associated infrastructure assets in the Midland Basin of west Texas. The Acquisition will complement and significantly expand our existing core position in the basin. The purchase price for the membership interests in Target is $980 million (the "Purchase Price"), subject to certain customary purchase price adjustments.

Pursuant to the Purchase Agreement, we will acquire approximately 24,783 net acres in Howard County, Texas that are predominantly contiguous; an estimated 6 MMBoe of proved developed producing reserves (based on internal estimates); and approximately 4,900 Boe per day of net production (as of July 2016) that is approximately 77% oil. The to be acquired leasehold has current production from wells in the Wolfcamp A, Wolfcamp B and Lower Spraberry formations, with a recently completed well producing approximately 1,600 Boe/d in the last 30 days. We have demonstrated superior operational execution in the Midland Basin and plan to utilize our extensive experience and expertise, including applying reservoir modeling, pad drilling and leading edge completion technologies to optimize the performance of the wells we expect to drill on the acquired assets.

We intend to fund the Acquisition with net proceeds from this offering, net proceeds from our Concurrent Convertible Notes Offering (as defined below), proceeds from asset sales pursuant to definitive agreements currently in place, proceeds from asset sales contemplated as part of our continued portfolio management (including the divestiture of our outside-operated position in the Eagle Ford shale), borrowings under our Fifth Amended and Restated Credit Agreement (as amended, the "Credit Agreement") by and among the Company, Wells Fargo Bank, National Association, as Administrative Agent, and the institutions named therein as lenders, or borrowings under the Bridge Facility (as defined below). There can be no assurances that any asset sales will be consummated.

The Acquisition is scheduled to close October 4, 2016 with an effective date of September 1, 2016, and is subject to the satisfaction of customary closing conditions. There can be no assurance that the transaction will close on the expected closing date or at all. Following the execution of the Purchase Agreement, we are required to deposit $49.0 million into an escrow account as a deposit to be applied against the Purchase Price at the closing of the Acquisition.

Neither the closing of this offering nor the closing of the Concurrent Convertible Notes Offering are conditioned upon, nor are they a condition to, the consummation of the Acquisition. If the Acquisition is delayed, not consummated or consummated in a manner different than described herein, the price of our shares of common stock may decline. In addition, if the Acquisition is not consummated, our management will have broad discretion in the application of the net proceeds of this offering. Accordingly, if you decide to purchase shares of our common stock in this offering, you should be willing to do so whether or not we complete the Acquisition.

Concurrent Convertible Notes Offering

Concurrently with this offering of our common stock, we are also making a public offering of $100.0 million principal amount of our % Convertible Senior Notes due 2021 ("Convertible Notes") pursuant to a separate prospectus supplement (the "Concurrent Convertible Notes Offering"). In that offering, we have granted the underwriters a 30-day option to purchase up to an additional $15.0 million principal amount of Convertible Notes. In connection with the pricing of the Concurrent

Convertible Notes Offering, the Company expects to enter into capped call transactions with option counterparties. The capped call transactions are generally expected to reduce potential dilution to our common stock upon any conversion of the Convertible Notes and/or offset any cash payments we are required to make in excess of the principal amount of converted notes, as the case may be, with such reduction and/or offset subject to a cap. The closing of this offering of our common stock is not conditioned upon the closing of the concurrent offering of our Convertible Notes, and the closing of the concurrent offering of Convertible Notes is not conditioned upon the closing of this offering of our common stock.

Bridge Facility

On August 8, 2016, we entered into a commitment letter by which a lender committed to make available to us a second lien bridge facility in a principal amount of up to $500 million ("Bridge Facility") until November 11, 2016, subject to the terms and conditions set forth in the commitment letter. If we decide to use this facility, the proceeds would be used to fund a portion of the Purchase Price of the Acquisition and the payment of fees and expenses of the Acquisition.

THE OFFERING


Issuer		SM Energy Company.
Common stock offered by us		15,000,000 shares.
Option to purchase additional shares		The underwriters also have the option to purchase up to an additional 2,250,000 shares from us on the same terms and conditions within 30 days from the date of this prospectus supplement.
Common stock outstanding following the offering(1)		83,466,823 shares (85,716,823 shares if the underwriters exercise their option to purchase additional shares in full).
Use of proceeds		We estimate that the net proceeds from this offering, after deducting the underwriting discount and commissions and our estimated offering expenses, will be approximately $ (or $ if the underwriters exercise their option to purchase additional shares in full).
		If the Acquisition is consummated, we intend to use the net proceeds from this offering to partially fund the Acquisition. If the Acquisition is not consummated, we intend to use the net proceeds from this offering for general corporate purposes, which may include, among other things, reducing indebtedness, acquiring properties, and funding a portion of our exploration and production activities and working capital. See "Use of proceeds."
		This offering is not conditioned upon the completion of the Acquisition, which, if completed, will occur subsequent to the closing of this offering, and the completion of this offering is not a condition to the completion of the Acquisition. In addition, there can be no assurance that we will consummate the Acquisition on the terms described herein or at all. If the Acquisition is not consummated, our management will have broad discretion in the application of the net proceeds of this offering.
Risk factors		Investing in our common stock involves substantial risk. You should carefully consider the risk factors set forth or cross-referenced in the sections entitled "Risk factors" beginning on page S-14 of this prospectus supplement and on page 4 of the accompanying prospectus, and the other information contained in this prospectus supplement and the accompanying prospectus and the documents incorporated by reference herein and therein, prior to making an investment in our common stock.
New York Stock Exchange symbol		"SM."

(1): The number of shares of common stock to be outstanding immediately following this offering is based on 68,466,823 shares outstanding as of July 31, 2016.

SUMMARY CONSOLIDATED HISTORICAL FINANCIAL INFORMATION

We derived the following summary historical financial data as of December 31, 2015 and 2014 and for the years ended December 31, 2015, 2014, and 2013, from our audited financial statements, which are incorporated by reference into this prospectus supplement and should be read in conjunction with Item 7, "Management's Discussion and Analysis of Financial Condition and Results of Operations" and Item 8, "Financial Statements and Supplementary Data" included in our 2015 Form 10-K, which is incorporated by reference herein. The summary historical balance sheet data as of December 31, 2013 has been derived from our audited financial statements included in our annual report on Form 10-K for the fiscal year ended December 31, 2013 but not included or incorporated by reference in this prospectus supplement. The financial data for the six months ended June 30, 2016 and 2015, respectively, and as of June 30, 2016 was derived from our unaudited condensed consolidated financial statements included in our Second Quarter 2016 Form 10-Q, which is incorporated by reference into this prospectus supplement. The Consolidated Balance Sheet data as of June 30, 2015 was derived from our unaudited condensed consolidated financial statements included in our Quarterly Report on Form 10-Q for the period ended June 30, 2015, which is not included or incorporated by reference in this prospectus supplement. The following summary historical financial data should be read in conjunction with Part I, Item 2, "Management's Discussion and Analysis of Financial Condition and Results of Operations" and Part I, Item 1, "Financial Statements" of our Second Quarter 2016 Form 10-Q.

	For the Six Months Ended June 30,						For the Years Ended December 31,

	2016			2015			2015			2014			2013
	(unaudited)
	(in thousands, except per share amounts)
Operating revenues:
Oil, gas, and NGL production revenue	$	502,965		$	834,571		$	1,499,905		$	2,481,544		$	2,199,550
Net gain (loss) on divestiture activity		(18,975	)		36,082			43,031			646			27,974
Marketed gas system revenue		—			9,482			9,485			24,897			60,039
Other operating revenues		900			1,945			4,544			15,220			5,811

Total operating revenues and other income		484,890			882,080			1,556,965			2,522,307			2,293,374
Operating expenses:
Oil, gas, and NGL production expense		293,134			369,836			723,633			715,878			597,045
Depletion, depreciation, amortization, and asset retirement obligation liability accretion		425,227			437,105			921,009			767,532			822,872
Exploration		28,460			62,948			120,569			129,857			74,104
Impairment of proved properties		269,785			68,440			468,679			84,480			172,641
Abandonment and impairment of unproved properties		2,349			17,446			78,643			75,638			46,105
Impairment of other property and equipment		—			—			49,369			—			—
General and administrative		60,438			86,244			157,668			167,103			149,551
Change in Net Profits Plan liability		1,865			(8,810	)		(19,525	)		(29,849	)		(21,842	)
Derivative (gain) loss		149,123			(73,238	)		(408,831	)		(583,264	)		(3,080	)
Marketed gas system expense		—			10,773			13,922			24,460			57,647
Other operating expenses		11,783			16,650			30,612			4,658			30,076

Total operating expenses		1,242,164			987,394			2,135,748			1,356,493			1,925,119
Income (loss) from operations		(757,274	)		(105,314	)		(578,783	)		1,165,814			368,255
Non-operating income (expense):
Other, net		11			596			649			(2,561	)		67
Interest expense		(65,123	)		(63,426	)		(128,149	)		(98,554	)		(89,711	)
Gain (loss) on extinguishment of debt		15,722			(16,578	)		(16,578	)		—			—

Income (loss) before income taxes		(806,664	)		(184,722	)		(722,861	)		1,064,699			278,611
Income tax (expense) benefit		290,773			74,156			275,151			(398,648	)		(107,676	)

Net income (loss)	$	(515,891	)	$	(110,566	)	$	(447,710	)	$	666,051		$	170,935



Basic weighted-average common shares outstanding		68,090			67,473			67,723			67,230			66,615
Diluted weighted-average common shares outstanding		68,090			67,473			67,723			68,044			67,998
Basic net income (loss) per common share	$	(7.58	)	$	(1.64	)	$	(6.61	)	$	9.91		$	2.57
Diluted net income (loss) per common share	$	(7.58	)	$	(1.64	)	$	(6.61	)	$	9.79		$	2.51

	As of June 30,					As of December 31,

	2016			2015		2015		2014			2013
	(unaudited)
	(in thousands)
Consolidated Balance Sheets Data:
Working capital	$	(16,367	)	$	3,551	$	216,464	$	(39,617	)	$	8,370
Total property and equipment, net	$	4,601,332		$	5,485,045	$	4,950,280	$	5,503,903		$	3,859,792
Total assets⁽¹⁾	$	5,044,475		$	6,213,618	$	5,621,643	$	6,483,145		$	4,678,023
Total noncurrent liabilities⁽¹⁾	$	3,374,798		$	3,503,154	$	3,466,717	$	3,411,830		$	2,432,071
Total stockholders' equity	$	1,348,836		$	2,188,307	$	1,852,401	$	2,286,655		$	1,606,821

(1): We adopted FASB ASU No. 2015-03, "Simplifying the Presentation of Debt Issuance Costs" effective November 1, 2015, which requires certain deferred financing costs to be presented on the balance sheets as a direct reduction from the carrying value of the related liability. 2013 amounts have been reclassified to conform with current period presentation in the 2015 Form 10-K.

	For the Six Months Ended June 30,						For the Years Ended December 31,

	2016			2015			2015			2014			2013
	(unaudited)
	(in thousands)
Consolidated Statements of Cash Flows:
Net cash provided by operating activities	$	256,873		$	549,508		$	978,352		$	1,456,575		$	1,338,514
Net cash used in investing activities	$	(351,254	)	$	(646,726	)	$	(1,144,639	)	$	(2,478,749	)	$	(1,192,903	)
Net cash provided by financing activities	$	94,381		$	97,180		$	166,185		$	740,046		$	130,711
Other Financial Data:
Adjusted EBITDAX⁽¹⁾	$	399,408		$	649,142		$	1,124,775		$	1,647,591		$	1,477,274

(1): See "—Reconciliation of Adjusted EBITDAX."

Reconciliation of Adjusted EBITDAX

Adjusted EBITDAX represents net income (loss) before interest expense, other non-operating income or expense, income taxes, depletion, depreciation, amortization, and accretion expense, exploration expense, impairments, non-cash stock-based compensation expense, derivative gains and losses net of settlements, change in the Net Profits Plan liability, and gains and losses on divestitures. Adjusted EBITDAX excludes certain items that we believe affect the comparability of operating results and can exclude items that are generally one-time in nature or whose timing and/or amount cannot be reasonably estimated. Adjusted EBITDAX is a non-GAAP measure that we present because we believe it provides useful additional information to investors and analysts, as a performance measure, for analysis of our ability to internally generate funds for exploration, development, acquisitions, and to service debt. We are also subject to financial covenants under our Credit Agreement based on certain adjusted EBITDAX ratios. In addition, adjusted EBITDAX is widely used by professional research analysts and others in the valuation, comparison, and investment recommendations of companies in the oil and gas exploration and production industry, and many investors use the published research of industry research analysts in making investment decisions. Our credit facility provides a material source of liquidity for us. Under the terms of our Credit Agreement, if we fail to comply with the covenants that establish a maximum permitted ratio of senior secured debt to adjusted EBITDAX and a minimum permitted ratio of adjusted EBITDAX to interest, we will be in default, an event that would prevent us from borrowing under our credit facility and would therefore materially limit our sources of

liquidity. In addition, if we default under our credit facility and are unable to obtain a waiver of that default from our lenders, lenders under that facility and under the indentures governing our outstanding Senior Notes would be entitled to exercise all of their remedies for a default.

Adjusted EBITDAX has limitations as an analytical tool and should not be considered in isolation or as a substitute for net income (loss), income (loss) from operations, net cash provided by (used in) operating activities, profitability, or liquidity measures prepared under GAAP. Because adjusted EBITDAX excludes some, but not all items that affect net income (loss) and may vary among companies, the adjusted EBITDAX amounts presented may not be comparable to similar metrics of other companies. Limitations to using adjusted EBITDAX as an analytical tool include:

•: Adjusted EBITDAX does not reflect current or future requirements for capital expenditures or capital commitments;
•: Adjusted EBITDAX does not reflect changes in, or cash requirements necessary to service interest or principal payments on debt;
•: Adjusted EBITDAX does not reflect income taxes;
•: Although depletion, depreciation and amortization are non-cash charges, the assets being depleted, depreciated or amortized will often have to be replaced in the future, and adjusted EBITDAX does not reflect any cash requirements for such replacements; and
•: Other companies in our industry may calculate adjusted EBITDAX differently than we do, limiting its usefulness as a comparison measure.

The following table provides reconciliations of our net income (loss) and net cash provided by operating activities to adjusted EBITDAX for the periods presented:

	For the Six Months Ended June 30,						For the Years Ended December 31,

	2016			2015			2015			2014			2013
	(unaudited)
	(in thousands)
Net income (loss) (GAAP)	$	(515,891	)	$	(110,566	)	$	(447,710	)	$	666,051		$	170,935
Interest expense		65,123			63,426			128,149			98,554			89,711
Other non-operating (income) expense, net		(11	)		(596	)		(649	)		2,561			(67	)
Income tax expense (benefit)		(290,773	)		(74,156	)		(275,151	)		398,648			107,676
Depletion, depreciation, amortization, and asset retirement obligation liability accretion		425,227			437,105			921,009			767,532			822,872
Exploration⁽¹⁾		25,013			59,500			113,158			122,577			65,888
Impairment of proved properties		269,785			68,440			468,679			84,480			172,641
Abandonment and impairment of unproved properties		2,349			17,446			78,643			75,638			46,105
Impairment of other property and equipment		—			—			49,369			—			—
Stock-based compensation expense		13,915			13,215			27,467			32,694			32,347
Derivative (gain) loss		149,123			(73,238	)		(408,831	)		(583,264	)		(3,080	)
Derivative settlement gain⁽²⁾		248,738			274,024			512,566			12,615			22,062
Change in Net Profits Plan liability		1,865			(8,810	)		(19,525	)		(29,849	)		(21,842	)
Net (gain) loss on divestiture activity		18,975			(36,082	)		(43,031	)		(646	)		(27,974	)
(Gain) loss on extinguishment of debt		(15,722	)		16,578			16,578			—			—
Other, net		1,692			2,856			4,054			—			—

Adjusted EBITDAX (Non-GAAP)		399,408			649,142			1,124,775			1,647,591			1,477,274

Interest expense		(65,123	)		(63,426	)		(128,149	)		(98,554	)		(89,711	)
Other non-operating income (expense), net		11			596			649			(2,561	)		67
Income tax (expense) benefit		290,773			74,156			275,151			(398,648	)		(107,676	)
Exploration⁽¹⁾		(25,013	)		(59,500	)		(113,158	)		(122,577	)		(65,888	)
Exploratory dry hole expense		(24	)		22,896			36,612			44,427			5,846
Amortization of deferred financing costs		1,930			3,892			7,710			6,146			5,390
Deferred income taxes		(291,014	)		(84,556	)		(276,722	)		397,780			105,555
Plugging and abandonment		(2,716	)		(3,386	)		(7,496	)		(8,796	)		(9,946	)
Loss on extinguishment of debt		—			(12,455	)		(12,455	)		—			—
Other, net		(1,016	)		(3,290	)		9,707			1,069			2,775
Changes in current assets and liabilities		(50,343	)		25,439			61,728			(9,302	)		14,828

Net cash provided by operating activities (GAAP)	$	256,873		$	549,508		$	978,352		$	1,456,575		$	1,338,514

(1): Stock-based compensation expense is a component of exploration expense and general and administrative expense on the statements of operations. Therefore, the exploration line items shown in the reconciliation above will vary from the amount shown on the statements of operations for the component of stock-based compensation expense recorded to exploration expense.

(2): Natural gas derivative settlements for the six months ended June 30, 2015, include a $15.3 million gain on the early settlement of future contracts as a result of divesting our remaining Mid-Continent assets during the second quarter of 2015. Natural gas derivative settlements for the years ended December 31, 2015, and 2014, include a $15.3 million gain and $5.6 million gain on the early settlement of futures contracts during the second quarter of 2015 and first quarter of 2014, respectively, as a result of divesting certain of our Mid-Continent assets.

SUMMARY RESERVE, PRODUCTION AND OPERATING DATA

Oil and Gas Reserves

The following table presents summary data with respect to our estimated net proved oil, gas, and NGL reserves as of the dates indicated. At least 80 percent of the PV-10 of our estimated proved reserves as of December 31, 2015, 2014 and 2013 was audited by Ryder Scott Company, L.P., which is a firm of independent reserve engineers. Our estimated proved reserves and related PV-10 as of December 31, 2015, 2014 and 2013 were determined in accordance with the reserve disclosure rules of the SEC using the 12-month unweighted arithmetic average of the first-day-of-the-month price for the periods of January 2015 through December 2015, January 2014 through December 2014 and January 2013 through December 2013, respectively, without giving effect to derivative transactions, and were held constant throughout the life of the properties.

	As of December 31,

	2015		2014		2013
Proved Reserves:⁽¹⁾
Oil (MMBbl)		145.3		169.7		126.6
Gas (Bcf)		1,264.0		1,466.5		1,189.3
NGLs (MMBbl)		115.4		133.5		103.9

Total (MMBOE)		471.3		547.7		428.7
Proved Developed (MMBOE)		244.5		286.8		208.9
Proved Undeveloped (MMBOE)		226.8		260.9		219.9
PV-10 (in millions)⁽²⁾	$	1,790.5	$	7,616.9	$	5,528.5

(1): The SEC defines proved oil and gas reserves (Rule 4-10(a) of Regulation S-X) as those quantities of oil and gas, which, by analysis of geoscience and engineering data, can be estimated with reasonable certainty to be economically producible—from a given date forward, from known reservoirs, and under existing economic conditions, operating methods, and government regulations—prior to the time at which contracts providing the right to operate expire, unless evidence indicates that renewal is reasonably certain, regardless of whether deterministic or probabilistic methods are used for the estimation.
(2): PV-10 is derived from the standardized measure of discounted future net cash flows, which is the most directly comparable GAAP financial measure. PV-10 is a computation of the standardized measure of discounted future net cash flows on a pre-tax basis. PV-10 is equal to the standardized measure of discounted future net cash flows at the applicable date, before deducting future income taxes, discounted at 10 percent. We believe that the presentation of PV-10 is relevant and useful to investors because it presents the discounted future net cash flows attributable to our estimated proved reserves prior to taking into account future corporate income taxes, and it is a useful measure for evaluating the relative monetary significance of our oil and natural gas assets. Further, investors may utilize the measure as a basis for comparison of the relative size and value of our reserves to other companies. We use this measure when assessing the potential return on investment related to our oil and natural gas assets. PV-10, however, is not a substitute for the standardized measure of discounted future net cash flows. Our PV-10 measure and the

standardized measure of discounted future net cash flows do not purport to present the fair value of our oil and natural gas reserves. Please see the definitions of standardized measure of discounted future net cash flows and PV-10 in the "Glossary of Oil and Natural Gas Terms."

The following table provides a reconciliation of PV-10 to the standardized measure of discounted future net cash flows as of December 31, 2015, 2014 and 2013:

	As of December 31,

	2015			2014			2013
	(in millions)
	(as adjusted)
Standardized measure of discounted future net cash flows	$	1,790.5		$	5,698.8		$	4,009.4
Add: 10 percent annual discount, net of income taxes		1,307.1			3,407.2			2,500.6
Add: future undiscounted income taxes		—			3,511.4			2,722.2

Undiscounted future net cash flows		3,097.6			12,617.4			9,232.2
Less: 10 percent annual discount without tax effect		(1,307.1	)		(5,000.5	)		(3,703.7	)

PV-10	$	1,790.5		$	7,616.9		$	5,528.5

Oil and Gas Production, Realized Prices and Production Costs

The following table summarizes our production volumes, net daily production, realized prices and production costs on a per BOE basis for the periods indicated.

	For the Six Months Ended June 30,						For the Years Ended December 31,

	2016			2015			2015			2014		2013
**Net production volumes⁽¹⁾**
Oil (MMBbl)		8.2			10.3			19.2			16.7		13.9
Gas (Bcf)		74.7			90.1			173.6			152.9		149.3
NGLs (MMBbl)		7.1			7.9			16.1			13.0		9.5
Equivalent (MMBOE)		27.7			33.3			64.2			55.1		48.3
**Average net daily production⁽¹⁾**
Oil (MBbl per day)		45.2			57.0			52.7			45.6		38.2
Gas (MMcf per day)		410.2			498.0			475.7			419.0		409.2
NGLs (MBbl per day)		38.8			43.8			44.0			35.6		26.0
Equivalent (MBOE per day)		152.4			183.7			175.9			151.1		132.4
*Realized price (before derivative settlements)*
Oil (per Bbl)	$	32.51		$	44.92		$	41.49		$	80.97	$	91.19
Gas (per Mcf)	$	1.83		$	2.65		$	2.57		$	4.58	$	3.93
NGLs (per Bbl)	$	14.05		$	16.76		$	15.92		$	33.34	$	35.95
Per BOE	$	18.14		$	25.10		$	23.36		$	45.01	$	45.50
*Realized price (after derivative settlements)*
Oil (per Bbl)	$	53.45		$	62.39		$	60.34		$	82.68	$	89.92
Gas (per Mcf)	$	2.80		$	3.46		$	3.28		$	4.40	$	4.14
NGLs (per Bbl)	$	14.63		$	19.39		$	17.61		$	34.18	$	36.66
Per BOE	$	27.11		$	33.34		$	31.34		$	45.23	$	45.92
**Per BOE data⁽¹⁾**
Production costs:
Lease operating expense	$	3.54		$	3.62		$	3.73		$	4.28	$	4.49
Transportation costs	$	6.00		$	5.86		$	6.02		$	6.11	$	5.34
Production taxes	$	0.80		$	1.25		$	1.13		$	2.13	$	2.19
Ad valorem tax expense	$	0.23		$	0.39		$	0.39		$	0.46	$	0.33
General and administrative	$	2.18		$	2.59		$	2.46		$	3.03	$	3.09
Depletion, depreciation, amortization, and asset retirement obligation liability accretion	$	15.34		$	13.14		$	14.34		$	13.92	$	17.02
Derivative settlement gain⁽²⁾	$	8.97		$	8.24		$	7.98		$	0.22	$	0.42
*Earnings per share information*
Basic net income (loss) per common share	$	(7.58	)	$	(1.64	)	$	(6.61	)	$	9.91	$	2.57
Diluted net income (loss) per common share	$	(7.58	)	$	(1.64	)	$	(6.61	)	$	9.79	$	2.51
Basic weighted-average common shares outstanding (in thousands)		68,090			67,473			67,723			67,230		66,615
Diluted weighted-average common shares outstanding (in thousands)		68,090			67,473			67,723			68,044		67,998

(1): Amounts may not calculate due to rounding.
(2): Natural gas derivative settlements for the six months ended June 30, 2015 include a $15.3 million gain on the early settlement of future contracts as a result of divesting our remaining Mid-Continent assets during the second quarter of 2015. These early settlements increased our derivative settlement gain by $0.46 per BOE for the six months ended June 30, 2015. Natural gas

An investment in our securities involves a significant degree of risk. Before you invest in our securities you should carefully consider those risk factors included in our 2015 Form 10-K, and our Quarterly Reports on Form 10-Q for the periods ended March 31, 2016 and June 30, 2016, which are incorporated herein by reference, and those risk factors set forth below, together with all of the other information included in this prospectus supplement and accompanying prospectus, and the documents we incorporate by reference, in evaluating an investment in our securities. If any of these risks were actually to occur, our business, financial condition or results of operations could be materially adversely affected. Additional risks not presently known to us or that we currently believe are immaterial may also significantly impair our business operations and financial condition. Please read "Cautionary Statement Regarding Forward-Looking Statements."

The pending Acquisition may not be completed as anticipated, or if completed, may not be beneficial to us.

The Acquisition is scheduled to close on October 4, 2016, and is subject to satisfaction of certain customary closing conditions and the satisfaction or waiver of other conditions, many of which are beyond our control. However, completion of the Acquisition is not a condition to completion of this offering of our common stock.

There are a number of risks and uncertainties relating to the Acquisition. For example, the Acquisition may not be completed, or may not be completed in the time frame, on the terms, or in the manner currently anticipated, as a result of a number of factors, including, among other things, the failure to satisfy one or more of the conditions to closing. There can be no assurance that such conditions will be satisfied or that the Acquisition will be consummated. In addition, the Purchase Agreement contains certain termination rights for each of SM and the Seller, including SM's right to terminate the Purchase Agreement if: (a) Seller's representations and warranties in the Purchase Agreement fail to be true and correct as of the closing date, except for such inaccuracies that would not, in the aggregate, have a material adverse effect, (b) Seller fails to perform or comply, in all material respects, with all obligations, agreements and covenants contained in the Purchase Agreement as to which such performance or compliance is required by Seller prior to the closing date, (c) a third-party institutes a material legal proceeding seeking to restrain, prohibit, enjoin or declare illegal the transactions contemplated by the Purchase Agreement, (d) a governmental authority or arbitrator issues an order, award or judgment to restrain, prohibit, enjoin or declare illegal the transactions contemplated by the Purchase Agreement, (e) the sum of (i) the aggregate amount of all reductions to the Purchase Price for title defects prior to the closing, less (ii) the aggregate amount of all title benefit amounts prior to closing, plus (iii) the aggregate amount of all reductions to the Purchase Price for environmental defects prior to the closing, exceeds 15% of the unadjusted Purchase Price, or (f) Seller shall have failed to deliver, or be ready, willing and able to deliver, the necessary closing documents.

If these conditions are not satisfied or waived, the transaction will not be consummated. There is no assurance that the Acquisition will close on or before that time, or at all, and the closing of this offering is not conditioned on the closing of the Acquisition. Accordingly, if you decide to purchase our common stock, you should be willing to do so whether or not we complete the Acquisition. The consummation of the Acquisition involves potential risks, including:

If we consummate the Acquisition and if these risks or other unanticipated liabilities were to materialize, any desired benefits of the Acquisition may not be fully realized, if at all, and our future financial performance and results of operations could be negatively impacted. We cannot assure you that we will realize value from the Acquisition that equals or exceeds the consideration paid.

If completed, the Acquisition may not achieve its intended results and may result in us assuming unanticipated liabilities. To date, we have conducted only limited diligence regarding the assets and liabilities we would assume in the Acquisition. These risks are heightened because the Acquisition, if consummated, would involve our acquisition of a material amount of acreage relative to our current acreage position and a material purchase price relative to our prior strategic activities.

We entered into the Purchase Agreement with the expectation that the Acquisition would result in various benefits, growth opportunities and synergies. Achieving the anticipated benefits of the Acquisition is subject to a number of risks and uncertainties. For example, under the Purchase Agreement, we have the opportunity to conduct customary environmental and title due diligence following the execution of the Purchase Agreement, but our diligence efforts to date have been limited. As a result, we may discover title defects or adverse environmental or other conditions of which we are currently unaware. Environmental, title and other problems could reduce the value of the properties to us, and, depending on the circumstances, we could have limited or no recourse to the Seller with respect to those problems. We would assume all of the Target's liabilities and would be entitled to indemnification in connection with those liabilities in only limited circumstances and in limited amounts. We cannot assure that such potential remedies will be adequate for any liabilities we incur, and such liabilities could be significant.

The risks involved in the Acquisition are heightened due to the size of the acquisition. The Acquisition, if consummated, would involve our acquisition of approximately 24,783 net acres in Howard County, Texas, which is a material amount of acreage relative to our current acreage position in the Permian Basin and a material purchase price relative to our prior strategic activities.

The anticipated future growth of our business will impose significant added responsibilities on management. The anticipated growth may place strain on our administrative and operational infrastructure. Our senior management's attention may be diverted from the management of daily operations to the integration of Seller's business operations and the assets acquired in the Acquisition. Our ability to manage our business and growth will require us to apply our operational, financial and management controls, reporting systems and procedures to the acquired business. We may also encounter risks, costs and expenses associated with any undisclosed or other unanticipated liabilities, and use more cash and other financial resources on integration and implementation activities than we anticipate. We may not be able to successfully integrate the Target's operations into our existing operations, successfully manage this additional acreage or realize the expected economic benefits of the Acquisition, which may have a material adverse effect on our business, financial condition and results of operations, including our cash available for distribution to our stockholders.

Actual reserves and production associated with the properties to be acquired in the Acquisition may be substantially less than we expect.

As with other acquisitions, the success of the Acquisition depends on, among other things, the accuracy of our assessment of the number and quality of the drilling locations associated with the properties to be acquired, future oil and natural gas prices, reserves and production, and future operating costs and various other factors. These assessments are necessarily inexact. Our assessment of certain of these factors is based in part on information provided to us by the sellers, including historical production data. Our independent reserve engineers have neither provided a report regarding the estimates of reserves nor an audit of the reserves with respect to the properties subject to the Acquisition. The assumptions on which our internal estimates have been based may prove to be incorrect in a number of material ways, resulting in our not realizing the expected benefits of the acquisition. In addition, the representations, warranties and indemnities of the Seller contained in the Purchase Agreement are limited, and we may not have recourse against the Seller in the event that the acreage is less valuable than we currently believe. As a result, we may not recover the Purchase Price for the Acquisition from the sale of production from the properties being acquired or recognize an acceptable return from such sales.

The development of the properties to be acquired will be subject to all of the risks and uncertainties associated with oil and natural gas activities as described in the "Risk Factors" section of our 2015 Form 10-K.

A significant portion of the value of the Acquisition is associated with undeveloped acreage that may not be economic.

A large portion of the acreage we are acquiring in the Acquisition is undeveloped, and our plans, development schedule and production schedule associated with the acreage may fail to materialize. As a result, our investment in these areas may not be as economic as we anticipate, and we could incur material write-downs of unevaluated properties.

We will incur significant transaction costs and expenses in connection with the Acquisition, and completion of the acquisition will increase our indebtedness.

We expect to incur a number of significant transaction-related costs and expenses associated with the Acquisition. We continue to assess the magnitude of these costs, and additional unanticipated costs may be incurred in the integration of the properties to be acquired, which may be significant.

We intend to finance a portion of the purchase price of the Acquisition and any transaction-related costs and expenses with the proceeds from this offering, and we expect that the remaining portion of the purchase price and related fees and expenses will be funded with net proceeds from our Concurrent Convertible Notes Offering, proceeds from asset sales pursuant to definitive agreements currently in place, asset sales contemplated as part of our continued portfolio management (including the divestiture of our outside operated position in the Eagle Ford shale), borrowings under our Credit Agreement or borrowings under the Bridge Facility. This increase in our indebtedness may reduce our flexibility to respond to changing business and economic conditions or to fund capital expenditures or working capital needs. There can be no assurance that we will be able to successfully consummate any divestitures, whether pending or contemplated.

The market price of our common stock may decline as a result of the Acquisition.

The market price of our common stock may decline as a result of the Acquisition if, among other things, we are unable to achieve the expected growth in earnings, or if the operational cost savings estimates in connection with the integration of Seller's business are not realized, or if the aggregate transaction costs related to the Acquisition are greater than expected. The market price also may

decline if we do not achieve the perceived benefits of the Acquisition as rapidly or to the extent anticipated by financial or industry analysts or if the effect of the Acquisition on our financial results is not consistent with the expectations of financial or industry analysts.

The price of our common stock may fluctuate significantly, which may result in losses for investors.

From January 1, 2016, to August 5, 2016, the low and high intraday trading prices per share of our common stock as reported by the New York Stock Exchange ranged from a low of $6.99 per share in February 2016 to a high of $35.60 per share in June 2016. We expect our stock to continue to be subject to fluctuations as a result of a variety of factors, including factors beyond our control. These factors include:

We may not meet the expectations of our stockholders and/or of securities analysts at some time in the future, and our stock price could decline as a result.

Our certificate of incorporation and by-laws have provisions that discourage corporate takeovers and could prevent stockholders from receiving a takeover premium on their investment, which could adversely affect the price of our common stock.

Delaware corporate law and our certificate of incorporation and by-laws contain provisions that may have the effect of delaying or preventing a change of control of us or our management. These provisions, among other things, provide for non-cumulative voting in the election of members of the Board of Directors and impose procedural requirements on stockholders who wish to make nominations for the election of directors or propose other actions at stockholder meetings. These provisions, alone or in combination with each other, may discourage transactions involving actual or potential changes of control, including transactions that otherwise could involve payment of a premium over prevailing market prices to stockholders for their common stock. As a result, these provisions could make it more difficult for a third party to acquire us, even if doing so would benefit our stockholders, which may limit the price investors are willing to pay in the future for shares of our common stock.

Shares eligible for future sale may cause the market price of our common stock to drop significantly, even if our business is doing well.

The potential for sales of substantial amounts of our common stock in the public market may have a materially adverse effect on our stock price. As of June 30, 2016, 68,183,128 shares of our common stock were freely tradable without substantial restriction or the requirement of future registration under the Securities Act. In addition, restricted stock units ("RSUs") providing for the issuance of up to a total of 503,480 shares of our common stock and 710,030 performance share units ("PSUs") were outstanding. The PSUs represent the right to receive, upon settlement of the PSUs after the completion of a three-year performance period, a number of shares of our common stock that may be

from zero to two times the number of PSUs granted, depending on the extent to which the underlying performance criteria have been achieved and the extent to which the PSUs have vested. As of June 30, 2016, there were 68,274,551 shares of our common stock outstanding.

Payment of future dividends remains at the discretion of our Board of Directors, and will continue to depend on our earnings, capital requirements, financial condition, and other factors. In addition, the payment of dividends is subject to a covenant in our credit facility limiting our annual cash dividends to no more than $50.0 million, and to covenants in the indentures for our Senior Notes that limit our ability to pay dividends beyond a certain amount. Our Board of Directors may determine in the future to reduce the current semi-annual dividend rate of $0.05 per share, or discontinue the payment of dividends altogether.

We believe that we currently are, and we expect to continue to be for the foreseeable future, a "United States real property holding corporation" for U.S. federal income tax purposes.

Generally, a corporation is a United States real property holding corporation for U.S. federal income tax purposes if the fair market value of its U.S. real property interests, as defined in the Code and applicable Treasury regulations, equals or exceeds 50% of the aggregate fair market value of its worldwide real property interests and its other assets used or held for use in a trade or business. We believe that we currently are, and we expect to continue to be for the foreseeable future, a "United States real property holding corporation" for U.S. federal income tax purposes. However, as long as our common stock is regularly traded on an established securities market, only a Non-U.S. Holder that actually or constructively owns, or owned at any time during the shorter of the five-year period ending on the date of the disposition or the Non-U.S. Holder's holding period for the common stock, more than 5% of the total fair market value of our common stock will be taxable on gain realized on the disposition of our common stock as a result of our status as a U.S. real property holding corporation. If our common stock were not considered to be so regularly traded during the calendar year in which the relevant disposition by a Non-U.S. Holder occurs, such holder (regardless of the percentage of our common stock owned) would be subject to U.S. federal income tax on a taxable disposition of our common stock, and a 15% withholding tax would apply to the gross proceeds from such disposition. Our common stock is currently listed on the NYSE and we believe that, for as long as we continue to be so listed, our common stock will be treated as regularly traded on an established securities market. See "Material U.S. Federal Income Tax Considerations for Non-U.S. Holders—Sale, Exchange or Other Taxable Disposition of Common Stock."

We estimate that the net proceeds from this offering, after deducting the underwriting discount and commissions and our estimated offering expenses, will be approximately $ (or $ if the underwriters exercise their option to purchase additional shares in full).

If the Acquisition is consummated, we intend to use the net proceeds from this offering to partially fund the Acquisition. If the Acquisition is not consummated, we intend to use the net proceeds from this offering for general corporate purposes, which may include, among other things, reducing indebtedness, acquiring properties, and funding a portion of our exploration and production activities and working capital. There can be no assurances that the Acquisition will be consummated or that the expected benefits of such transaction will be realized. The closing of this offering is not conditioned on, nor is it a condition to, the consummation of the Acquisition. If the Acquisition is delayed, not consummated or consummated in a manner different than described herein, the price of our shares of common stock may decline. In addition, if the Acquisition is not consummated, our management will have broad discretion in the application of the net proceeds of this offering. Accordingly, if you decide to purchase shares of our common stock in this offering, you should be willing to do so whether or not we complete the Acquisition. See "Summary—Recent developments" for more information regarding the Acquisition.

You should read this table in conjunction with our consolidated unaudited financial statements incorporated by reference in this prospectus supplement and the accompanying prospectus and the prospectus supplement related to our Concurrent Convertible Notes Offering.

	As of June 30, 2016

(in millions)	Historical			As Adjusted			As Further Adjusted
Cash and cash equivalents	$	0.018		$	0.018		$	0.018

Long-term debt:
Revolving credit facility due 2019⁽¹⁾⁽²⁾		330.5			330.5			330.5
6.50% Notes due 2021		347.0			347.0			347.0
6.125% Notes due 2022		561.8			561.8			561.8
6.50% Notes due 2023		395.0			395.0			395.0
5.00% Notes due 2024		500.0			500.0			500.0
5.625% Notes due 2025		500.0			500.0			500.0
% Convertible Notes due 2021		—			—			100.0
Unamortized discount and unamortized debt issuance costs		(31.2	)		(31.2	)		(31.2	)

Total long-term debt	$	2,603.1		$	2,603.1		$	2,703.1

Stockholders' equity:
Common stock, par value $0.01 per share; 200.0 million shares authorized; 68,274,551 actual shares issued or 83,274,551 actual shares issued as adjusted and as further adjusted, respectively;	$	0.7		$	0.8		$	0.8
Additional paid-in capital⁽³⁾		321.8
Retained earnings		1,040.2			1,040.2			1,040.2
Accumulated other comprehensive (loss)		(13.9	)		(13.9	)		(13.9	)

Total stockholder's equity	$	1,348.8		$			$

Total capitalization	$	3,951.9		$			$

Our common stock is listed on the NYSE under the symbol "SM." The following table shows, for the periods indicated, the high and low reported sales prices for our common stock, as reported on the NYSE.

	Sales Price

	High		Low
2014:
First quarter	$	90.22	$	69.03
Second quarter	$	85.39	$	71.00
Third quarter	$	90.38	$	74.57
Fourth quarter	$	79.89	$	29.41
2015:
First quarter	$	53.31	$	31.01
Second quarter	$	60.28	$	43.70
Third quarter	$	45.98	$	18.21
Fourth quarter	$	42.23	$	18.06
2016:
First quarter	$	20.65	$	6.99
Second quarter	$	35.60	$	17.04
Third quarter (through August 5, 2016)	$	30.36	$	23.58

On August 5, 2016, the last reported trading price of our common stock on the NYSE was $29.30 per share. As of July 29, 2016, there were approximately 68 holders of record of our common stock.

We have paid cash dividends to our stockholders every year since 1940. We paid annual dividends of $0.05 per share in each of the years 1998 through 2004. We paid annual dividends of $0.10 per share in each of the years 2005 through 2015. We expect our practice of paying dividends on our common stock to continue, although the payment and amount of future dividends will continue to depend on our earnings, cash flow, capital requirements, financial condition, and other factors, including the discretion of our Board of Directors.

In addition, the payment of dividends is subject to covenants in our credit facility that limit our annual dividend payment to no more than $50.0 million per year. We are also subject to certain covenants under our Senior Notes that restrict certain payments, including dividends; however, the first $6.5 million of dividends paid each year are not restricted by this covenant. Based on our current performance, we do not anticipate that these covenants will restrict future annual dividend payments in amounts not to exceed $0.10 per share of common stock. Dividends are currently paid on a semi-annual basis. Dividends paid totaled $3.4 million for the six months ended June 30, 2016, and $6.8 million and $6.7 million for the years ended December 31, 2015, and December 31, 2014, respectively.

The following discussion is a summary of the anticipated material U.S. federal income tax considerations generally applicable to the purchase, ownership and disposition of our common stock by Non-U.S. Holders (as defined below). This summary deals only with our common stock held as capital assets by holders who purchase common stock in this offering. For purposes of this summary, a "Non-U.S. Holder" means a beneficial owner of our common stock that, for U.S. federal income tax purposes, is an individual, corporation, estate or trust and is not any one of the following:

This discussion does not cover all aspects of U.S. federal income taxation that may be relevant to the purchase, ownership or disposition of our common stock by prospective investors in light of their particular circumstances. In particular, this discussion does not address all of the tax considerations that may be relevant to certain types of investors subject to special treatment under U.S. federal income tax laws, such as:

Furthermore, this summary is based upon the provisions of the Internal Revenue Code of 1986, as amended, or the Code, the Treasury regulations promulgated thereunder and administrative and judicial interpretations thereof, all as of the date hereof. Such authorities may be repealed, revoked, modified or subject to differing interpretations, possibly on a retroactive basis, so as to result in U.S. federal income tax consequences different from those discussed below. This discussion does not address any state, local or non-U.S. tax considerations or tax considerations as to U.S. federal non-income taxes (such as the U.S. estate and gift tax or the U.S. Medicare tax on certain investment income) or any tax treaties. We have not sought any ruling from the Internal Revenue Service, or IRS, with respect to the statements made or the conclusions reached in the following summary, and there can be no assurance that the IRS or a court will agree with such statements or conclusions.

If a partnership or other entity or arrangement treated as a partnership for U.S. federal income tax purposes holds our common stock, the U.S. federal income tax treatment of a partner in such partnership will generally depend upon the status of the partner and the activities of the partnership. If you are a partnership or a partner of a partnership holding our common stock, we particularly urge you to consult your tax advisors.

If you are considering the purchase of our common stock, we urge you to consult your tax advisors concerning the particular U.S. federal income tax consequences to you of the purchase, ownership and disposition of our common stock, as well as any consequences to you arising under state, local and non-U.S. tax laws, under U.S. non-income tax laws and under any applicable tax treaty.

Distributions paid to you on our common stock, other than certain pro rata distributions of common stock, will be included in ordinary dividend income when received (to the extent paid out of our current or accumulated earnings and profits, as determined for U.S. federal income tax purposes) and generally will be subject to U.S. federal withholding tax at a 30% rate, or such lower rate as may be specified by an applicable tax treaty as to which you appropriately claim the benefit. However, dividends that are effectively connected with a trade or business you conduct within the United States, and, if certain tax treaties apply and you appropriately claim benefits thereunder, are attributable to a permanent establishment maintained by you in the United States, are not subject to the U.S. federal withholding tax, but instead are subject to U.S. federal income tax on a net income basis at the applicable graduated individual or corporate rates. Special certification and disclosure requirements must be satisfied for effectively connected income to be exempt from withholding. If you are a corporation, any such effectively connected dividends that you receive may be subject to an additional branch profits tax at a 30% rate or such lower rate as may be specified by an applicable income tax treaty as to which you appropriately claim the benefit. To the extent distributions exceed our current and accumulated earnings and profits, the distributions will be treated as a non-taxable return of capital to the extent of your tax basis in our common stock and thereafter as capital gain from the sale or exchange of such common stock. See "—Sale, Exchange or Other Taxable Disposition of Common Stock."

If you wish to claim the benefit of an applicable treaty rate for dividends paid on our common stock, you must provide the withholding agent with a properly executed IRS Form W-8BEN or W-8BEN-E (or other applicable form), claiming an exemption from or reduction in withholding under the applicable income tax treaty.

If you are eligible for a reduced rate of U.S. federal withholding tax pursuant to an applicable income tax treaty, you may obtain a refund of any excess amounts withheld by timely providing the required information to the IRS.

Subject to the discussion below under "—Foreign Account Tax Compliance Act," you generally will not be subject to U.S. federal income tax with respect to gain recognized on a sale, exchange or other taxable disposition of shares of our common stock unless:

If you are an individual and are described in the first bullet above, you will be subject to tax on any gain derived from the sale, exchange or other taxable disposition at the graduated U.S. federal income tax rates generally applicable to U.S. citizens or residents. If you are an individual and are described in the second bullet above, you will generally be subject to a flat 30% tax on any gain derived from the sale, exchange or other taxable disposition that may be offset by U.S. source capital losses (even though you are not considered a resident of the United States). If you are a corporation and are described in the first bullet above, you will be subject to tax on your gain at the U.S. federal income tax rates generally applicable to U.S. corporations and, in addition, may be subject to the branch profits tax on your effectively connected earnings and profits for the taxable year, which would include such gain, at a rate of 30% or at such lower rate as may be specified by the applicable income tax treaty, subject to adjustments.

Generally, a corporation is a United States real property holding corporation for U.S. federal income tax purposes if the fair market value of its U.S. real property interests, as defined in the Code and applicable Treasury regulations, equals or exceeds 50% of the aggregate fair market value of its worldwide real property interests and its other assets used or held for use in a trade or business. We believe that we currently are, and we expect to continue to be for the foreseeable future, a "United States real property holding corporation" for U.S. federal income tax purposes. Our common stock is currently listed on the NYSE and we believe that, for as long as we continue to be so listed, our common stock will be treated as regularly traded on an established securities market. If we are a United States real property holding corporation, and if our common stock continues to be regularly traded on an established securities market, only a Non-U.S. Holder that actually or constructively owns, or owned at any time during the shorter of the five-year period ending on the date of the disposition or the Non-U.S. Holder's holding period for the common stock, more than 5% of the total fair market value of our common stock will be taxable on gain realized on the disposition of our common stock as a result of our status as a United States real property holding corporation. If, during the calendar year in which the relevant disposition by a Non-U.S. Holder occurs, we are a United States real property holding corporation and if our common stock ceases to be regularly traded, you generally would be

subject to U.S. federal income tax on a taxable disposition of our common stock (regardless of the amount of our common stock owned), and transferees of our common stock generally would be required to withhold 15% of the gross proceeds payable to you. The gain from the disposition would be subject to regular U.S. income tax as if you were a United States holder, and you would be required to file a U.S. tax return with respect to such gain.

You should consult your tax advisors with respect to the application of the foregoing rules to your ownership and disposition of our common stock.

Withholding at a rate of 30% will be required on dividends in respect of, and, after December 31, 2018, withholding at a rate of 30% will be required on gross proceeds from the sale or other disposition of, our common stock held by or through certain foreign financial institutions (including investment funds), unless such institution enters into an agreement with the U.S. Treasury Department to report, on an annual basis, information with respect to interests in, and accounts maintained by, the institution that are owned by certain U.S. persons and by certain non-U.S. entities that are wholly or partially owned by U.S. persons and to withhold on certain payments. An intergovernmental agreement between the United States and an applicable foreign country, or future Treasury regulations, may modify these requirements. Accordingly, the entity through which our common stock is held will affect the determination of whether such withholding is required. Similarly, dividends in respect of, and, after December 31, 2018, gross proceeds from the sale or other disposition of, our common stock held by an investor that is a non-financial non-U.S. entity that does not qualify under certain exemptions will be subject to withholding at a rate of 30%, unless such entity either (i) certifies that such entity does not have any "substantial United States owners" or (ii) provides certain information regarding the entity's "substantial United States owners." Prospective investors should consult their tax advisors regarding the possible implications of these rules on their investment in our common stock.

You may be subject to information reporting and backup withholding with respect to any dividends on, and the proceeds from dispositions of, our common stock paid to you, unless you comply with certain reporting procedures (usually satisfied by providing the appropriate form from the IRS Form W-8 series) or otherwise establish an exemption. Additional rules relating to information reporting requirements and backup withholding with respect to the payment of proceeds from the disposition of shares of our common stock will apply as follows:

In addition, the amount of any dividends paid to you and the amount of tax, if any, withheld from such payment generally must be reported annually to you and the IRS. The IRS may make such

information available under the provisions of an applicable income tax treaty to the tax authorities in the country in which you reside. Any amounts withheld under the backup withholding rules are treated as a credit against your actual U.S. federal income tax liability and any amounts withheld in excess of your actual U.S. federal income tax liability will be allowed as a refund provided the required information is timely furnished by you to the IRS. Non-U.S. Holders should consult their tax advisors regarding the filing of a U.S. tax return for claiming a refund of such backup withholding.

The following is a summary of certain considerations associated with the purchase of our common stock by employee benefit plans that are subject to Title I of the U.S. Employee Retirement Income Security Act of 1974, as amended ("ERISA"), plans, individual retirement accounts and other arrangements that are subject to Section 4975 of the Code or provisions under any federal, state, local, non-U.S. or other laws or regulations that are similar to such provisions of ERISA or the Code (collectively, "Similar Laws"), and entities whose underlying assets are considered to include "plan assets" of any such plan, account or arrangement (each, a "Plan").

ERISA and the Code impose certain duties on persons who are fiduciaries or other interested parties of a Plan subject to Title I of ERISA or Section 4975 of the Code (an "ERISA Plan") and prohibit certain transactions involving the assets of an ERISA Plan and its fiduciaries or other interested parties. Under ERISA and the Code, any person who exercises any discretionary authority or control over the administration of such an ERISA Plan or the management or disposition of the assets of such an ERISA Plan, or who renders investment advice for a fee or other compensation to such an ERISA Plan, is generally considered to be a fiduciary of the ERISA Plan.

In considering an investment in our common stock of a portion of the assets of any Plan, a fiduciary should determine whether the investment is in accordance with the documents and instruments governing the Plan and the applicable provisions of ERISA, the Code or any Similar Law relating to a fiduciary's duties to the Plan including, without limitation, the prudence, diversification, delegation of control and prohibited transaction provisions of ERISA, the Code and any other applicable Similar Laws.

Section 406 of ERISA and Section 4975 of the Code prohibit ERISA Plans from engaging in specified transactions involving plan assets with persons or entities who are "parties in interest," within the meaning of ERISA, or "disqualified persons," within the meaning of Section 4975 of the Code, unless an exemption is available. A party in interest or disqualified person who engages in a non-exempt prohibited transaction may be subject to excise taxes and other penalties and liabilities under ERISA and the Code. In addition, the fiduciary of the ERISA Plan that engaged in such a non-exempt prohibited transaction may be subject to penalties and liabilities under ERISA and the Code. The acquisition and/or holding of our common stock by an ERISA Plan with respect to which we or the underwriters are considered a party in interest or a disqualified person may constitute or result in a direct or indirect prohibited transaction under Section 406 of ERISA and/or Section 4975 of the Code, unless the investment is acquired and is held in accordance with an applicable statutory, class or individual prohibited transaction exemption. In this regard, the U.S. Department of Labor has issued prohibited transaction class exemptions, or "PTCEs," that may apply to the acquisition and holding of our common stock. These class exemptions include, without limitation, PTCE 84-14 respecting transactions determined by independent qualified professional asset managers, PTCE 90-1 respecting insurance company pooled separate accounts, PTCE 91-38 respecting bank collective investment funds, PTCE 95-60 respecting life insurance company general accounts and PTCE 96-23 respecting

transactions determined by in-house asset managers. In addition, Section 408(b)(17) of ERISA and Section 4975(d)(20) of the Code provide relief from the prohibited transaction provisions of ERISA and Section 4975 of the Code for certain transactions, provided that neither the issuer of the securities nor any of its affiliates (directly or indirectly) have or exercise any discretionary authority or control or render any investment advice with respect to the assets of any ERISA Plan involved in the transaction and provided further that the ERISA Plan pays no more than adequate consideration in connection with the transaction. There can be no assurance that all of the conditions of any such exemptions will be satisfied.

Because of the foregoing, our common stock should not be purchased or held by any person investing "plan assets" of any Plan, unless such purchase and holding will not constitute a non-exempt prohibited transaction under ERISA and the Code or similar violation of any applicable Similar Laws.

Accordingly, by acceptance of our common stock, each purchaser and subsequent transferee of our common stock will be deemed to have represented and warranted that either (i) no portion of the assets used by such purchaser or transferee to acquire or hold our common stock constitutes assets of any Plan or (ii) the purchase and holding of our common stock by such purchaser or transferee will not constitute a non-exempt prohibited transaction under Section 406 of ERISA or Section 4975 of the Code or a similar violation under any applicable Similar Laws.

The foregoing discussion is general in nature and is not intended to be all inclusive, nor should it be construed as legal advice. Due to the complexity of these rules and the penalties that may be imposed upon persons involved in non-exempt prohibited transactions, it is particularly important that fiduciaries or other persons considering purchasing our common stock on behalf of, or with the assets of, any Plan, consult with their counsel regarding the potential applicability of ERISA, Section 4975 of the Code and any Similar Laws to such investment and whether an exemption would be applicable to the purchase and holding of our common stock. Further, this prospectus contains no recommendation as to the suitability of our common stock as an investment in any Plan under ERISA and any Similar Laws.

Wells Fargo Securities, LLC, Merrill Lynch, Pierce, Fenner & Smith Incorporated and J.P. Morgan Securities LLC are acting as the representatives of the underwriters named below. Under the terms of an underwriting agreement, which we will file as an exhibit to our current report on Form 8-K and incorporate by reference in this prospectus supplement and the accompanying base prospectus, each of the underwriters named below has severally agreed to purchase from us the shares of our common stock shown opposite its name below.

Underwriters		Shares of Common Stock

Wells Fargo Securities, LLC
Merrill Lynch, Pierce, Fenner & Smith Incorporated
J. P. Morgan Securities LLC
Barclays Capital Inc.
BBVA Capital Markets, LLC
RBC Capital Markets, LLC






Total			15,000,000

The underwriting agreement provides that the underwriters' obligation to purchase the shares of our common stock depends on the satisfaction of the conditions contained in the underwriting agreement including (i) the obligation to purchase all of the shares of our common stock offered hereby (other than those shares of our common stock covered by their option to purchase additional shares of our common stock as described below), if any of the shares of our common stock are purchased; (ii) the representations and warranties made by us to the underwriters are true; (iii) there is no material change in our business or the financial markets; and (iv) we deliver customary closing documents to the underwriters.

The following table summarizes the underwriting discounts and commissions we will pay to the underwriters. These amounts are shown assuming both no exercise and full exercise of the underwriters' option to purchase additional shares of our common stock. The underwriting fee is the difference between the initial price to the public and the amount the underwriters will pay to us for the shares of our common stock.

The representatives of the underwriters have advised us that the underwriters propose to offer the shares of our common stock directly to the public at the public offering price on the cover of this prospectus supplement and to selected dealers, which may include the underwriters, at such offering price less a selling concession not in excess of $ per share. After the offering, the representatives may change the offering price and other selling terms. Sales of shares of our common stock made outside of the United States may be made by affiliates of the underwriters. The offering of the shares

of our common stock by the underwriters is subject to receipt and acceptance and subject to the underwriters' right to reject any order in whole or in part.

The expenses of this offering that are payable by us are estimated to be $300,000 (excluding underwriting discounts and commissions).

We have granted the underwriters an option exercisable for 30 days after the date of the underwriting agreement, to purchase, from time to time, in whole or in part, up to an aggregate of 2,250,000 shares of our common stock at the public offering price less underwriting discounts and commissions. To the extent that this option is exercised, each underwriter will be obligated, subject to certain conditions, to purchase its pro rata portion of these additional shares of our common stock from us based on the underwriter's percentage underwriting commitment in the offering as indicated in the table at the beginning of this Underwriting section.

We have agreed that we will not (i) offer, sell, contract or grant any option to sell, pledge, transfer or establish an open "put equivalent position within the meaning of Rule 16a-1 under the Exchange Act, or otherwise dispose of, directly or indirectly, or file with the SEC a registration statement under the Securities Act relating to, any shares of our common stock or securities convertible into or exchangeable or exercisable for any shares of our common stock, or publicly disclose the intention to make any offer, sale, pledge, disposition, or filing or (ii) enter any swap or any other agreement or any transaction that transfers, in whole or in part, the economic consequence of ownership of shares of our common stock, whether any such swap or transaction described in clause (i) or (ii) is to be settled by delivery of shares of our common stock or such other securities, in cash or otherwise, without the prior written consent of the representatives for a period of 60 days after the date of this prospectus supplement, except that (1) we may issue and sell shares of our common stock upon the conversion or exchange of convertible or exchangeable securities outstanding on the date of this prospectus supplement, (2) we may issue and sell shares of our common stock upon the exercise of options or warrants outstanding on the date of this prospectus supplement or as a result of permitted grants or issuances as described in the following clause (3), and (3) we may grant or issue stock options and warrants, restricted stock, phantom stock, and other securities to our employees, officers, and directors pursuant to the terms of a plan in effect on the date of this prospectus supplement.

Our directors and certain of our executive officers have agreed that they will not offer, sell, contract to sell, pledge, or otherwise dispose of, directly or indirectly, any shares of our common stock or securities convertible into or exchangeable or exercisable for any shares of our common stock, enter into a transaction that would have the same effect, or enter into any swap, hedge, or other arrangement that transfers, in whole or in part, any of the economic consequences of ownership of our common stock, whether any of these transactions are to be settled by delivery of our common stock or other securities, in cash, or otherwise, or publicly disclose the intention to make any offer, sale, pledge, or disposition, or to enter into any transaction, swap, hedge, or other arrangement, without, in each case, the prior written consent of Wells Fargo Securities, LLC for a period of 60 days after the date of this prospectus supplement, except (i) that such executive officers and directors may sell shares acquired by such executive officers and directors in the open market after the date of this prospectus supplement, provided that no filing under the Exchange Act, shall be required or shall be voluntarily made in connection with any such sale, pledge or disposition (other than a filing on a Form 5, Schedule 13D or Schedule 13G (or 13D/A or 13G/A) made after the expiration of the 60-day restricted period) and (ii) such executive officers and directors may sell, pledge or dispose of any shares of our common stock to a family member, family partnership (including a limited partnership), other family investment entity or trust, provided that in connection with any such sale, pledge or disposition (A) the recipient agrees

to be bound in writing by the terms of such agreement prior to such sale, pledge or disposition and (B) the transfer is not a sale, pledge or disposition of value.

Wells Fargo Securities, LLC, in its sole discretion, may release the shares of our common stock and other securities subject to the lock-up agreements described above in whole or in part at any time with or without notice. When determining whether or not to release our common stock and other securities from lock-up agreements, Wells Fargo Securities, LLC will consider, among other factors, the holder's reasons for requesting the release, the number of shares of our common stock and other securities for which the release is being requested and market conditions at the time.

We have agreed to indemnify the underwriters against certain liabilities, including liabilities under the Securities Act, and to contribute to payments that the underwriters may be required to make for these liabilities.

The representatives may engage in stabilizing transactions, short sales and purchases to cover positions created by short sales, and penalty bids or purchases for the purpose of pegging, fixing or maintaining the price of the shares of our common stock, in accordance with Regulation M under the Securities Exchange Act:

In addition, in these stabilizing transactions the underwriters may purchase our common stock prior to the pricing of this offering. These stabilizing transactions, syndicate covering transactions and penalty bids may have the effect of raising or maintaining the market price of our common stock or

preventing or retarding a decline in the market price of the shares of our common stock. As a result, the price of our shares of common stock sold in the offering may be higher than the price that might otherwise exist in the open market. These transactions may be effected on the NYSE or otherwise and, if commenced, may be discontinued at any time.

Neither we nor any of the underwriters make any representation or prediction as to the direction or magnitude of any effect that the transactions described above may have on the price of the shares of our common stock. In addition, neither we nor any of the underwriters make any representation that the representatives will engage in these stabilizing transactions or that any transaction, once commenced, will not be discontinued without notice.

This prospectus supplement and the accompanying base prospectus in electronic format may be made available on the Internet sites or through other online services maintained by one or more of the underwriters and/or selling group members participating in this offering, or by their affiliates. In those cases, prospective investors may view offering terms online and, depending upon the particular underwriter or selling group member, prospective investors may be allowed to place orders online. The underwriters may agree with us to allocate a specific number of shares of our common stock for sale to online brokerage account holders. Any such allocation for online distributions will be made by the representatives on the same basis as other allocations.

Other than the prospectus supplement and the accompanying base prospectus in electronic format, the information on any underwriter's or selling group member's web site and any information contained in any other web site maintained by an underwriter or selling group member is not part of this prospectus supplement, the accompanying base prospectus or the registration statement of which this prospectus supplement and the accompanying base prospectus form a part, has not been approved and/or endorsed by us or any underwriter or selling group member in its capacity as underwriter or selling group member and should not be relied upon by investors.

If you purchase shares of our common stock offered by this prospectus supplement and the accompanying base prospectus, you may be required to pay stamp taxes and other charges under the laws and practices of the country of purchase, in addition to the offering price listed on the cover page of this prospectus supplement and the accompanying base prospectus.

The underwriters and certain of their affiliates are full service financial institutions engaged in various activities, which may include securities trading, commercial and investment banking, financial advisory, investment management, investment research, principal investment, hedging, financing and brokerage activities. The underwriters and certain of their affiliates have, from time to time, performed, and may in the future perform, various commercial and investment banking and financial advisory services for the issuer and its affiliates, for which they received or may in the future receive customary fees and expenses. An affiliate of each of the underwriters is a lender under our credit facility. In addition, the underwriters in this offering are also serving as underwriters in our Concurrent Convertible Notes Offering.

In the ordinary course of their various business activities, the underwriters and certain of their affiliates may make or hold a broad array of investments and actively trade debt and equity securities (or related derivative securities) and financial instruments (including bank loans) for their own account and for the accounts of their customers, and such investment and securities activities may involve securities and/or instruments of the issuer or its affiliates. If the underwriters or their affiliates have a

lending relationship with us, certain of the underwriters or their affiliates may hedge their credit exposure to us consistent with their customary risk management policies. Typically, the underwriters and their affiliates would hedge such exposure by entering into transactions which consist of either the purchase of credit default swaps or the creation of short positions in our securities or the securities of our affiliates, including potentially the shares of our common stock offered hereby. Any such credit default swaps or short positions could adversely affect future trading prices of the shares of our common stock offered hereby. The underwriters and certain of their affiliates may also communicate independent investment recommendations, market color or trading ideas and/or publish or express independent research views in respect of such securities or instruments and may at any time hold, or recommend to clients that they acquire, long and/or short positions in such securities and instruments.

This prospectus does not constitute an offer to sell to, or a solicitation of an offer to buy from, anyone in any country or jurisdiction (i) in which such an offer or solicitation is not authorized, (ii) in which any person making such offer or solicitation is not qualified to do so or (iii) in which any such offer or solicitation would otherwise be unlawful. No action has been taken that would, or is intended to, permit a public offer of the shares of our common stock or possession or distribution of this prospectus or any other offering or publicity material relating to the shares of our common stock in any country or jurisdiction (other than the United States) where any such action for that purpose is required. Accordingly, each underwriter has undertaken that it will not, directly or indirectly, offer or sell any shares of our common stock or have in its possession, distribute or publish any prospectus, form of application, advertisement or other document or information in any country or jurisdiction except under circumstances that will, to the best of its knowledge and belief, result in compliance with any applicable laws and regulations and all offers and sales of shares of our common stock by it.

Our shares of common stock may not be offered or sold in Hong Kong by means of this prospectus or any other document other than to (a) professional investors as defined in the Securities and Futures Ordinance of Hong Kong (Cap. 571, Laws of Hong Kong) ("SFO") and any rules made under the SFO or (b) in other circumstances which do not result in this prospectus being deemed to be a "prospectus," as defined in the Companies Ordinance of Hong Kong (Cap. 32, Laws of Hong Kong) ("CO"), or which do not constitute an offer to the public within the meaning of the CO or the SFO; and no person has issued or had in possession for the purposes of issue, or will issue or has in possession for the purposes of issue, whether in Hong Kong or elsewhere, any advertisement, invitation or document relating to our shares of common stock which is directed at, or the contents of which are likely to be accessed or read by, the public of Hong Kong (except if permitted to do so under the securities laws of Hong Kong) other than with respect to our shares of common stock which are or are intended to be disposed of only to persons outside Hong Kong or only to professional investors as defined in the SFO.

No placement document, prospectus, product disclosure statement or other disclosure document has been lodged with the Australian Securities and Investments Commission ("ASIC"), in relation to the offering. This prospectus does not constitute a prospectus, product disclosure statement or other disclosure document under the Corporations Act 2001 (the "Corporations Act"), and does not purport to include the information required for a prospectus, product disclosure statement or other disclosure document under the Corporations Act.

Any offer in Australia of the shares may only be made to persons (the "Exempt Investors") who are "sophisticated investors" (within the meaning of section 708(8) of the Corporations Act), "professional investors" (within the meaning of section 708(11) of the Corporations Act) or otherwise pursuant to one or more exemptions contained in section 708 of the Corporations Act so that it is lawful to offer the shares without disclosure to investors under Chapter 6D of the Corporations Act.

The shares applied for by Exempt Investors in Australia must not be offered for sale in Australia in the period of 12 months after the date of allotment under the offering, except in circumstances where disclosure to investors under Chapter 6D of the Corporations Act would not be required pursuant to an exemption under section 708 of the Corporations Act or otherwise or where the offer is pursuant to a disclosure document which complies with Chapter 6D of the Corporations Act. Any person acquiring shares must observe such Australian on-sale restrictions.

This prospectus contains general information only and does not take account of the investment objectives, financial situation or particular needs of any particular person. It does not contain any securities recommendations or financial product advice. Before making an investment decision, investors need to consider whether the information in this prospectus is appropriate to their needs, objectives and circumstances, and, if necessary, seek expert advice on those matters.

In relation to each Member State of the European Economic Area which has implemented the Prospectus Directive (each, a "Relevant Member State"), with effect from and including the date on which the Prospectus Directive is implemented in that Relevant Member State (the "Relevant Implementation Date") no offer of our shares of common stock may be made to the public in that Relevant Member State other than:

This prospectus has been prepared on the basis that any offer of shares of common stock in any Relevant Member State will be made pursuant to an exemption under the Prospectus Directive from the requirement to publish a prospectus for offers of our shares of common stock. Accordingly any person making or intending to make an offer in that Relevant Member State of our shares of common stock which are the subject of the offering contemplated in this prospectus may only do so in circumstances in which no obligation arises for the Company or any of the underwriters to publish a prospectus pursuant to Article 3 of the Prospectus Directive in relation to such offer. Neither the Company nor the underwriters have authorized, nor do they authorize, the making of any offer of our shares of common stock in circumstances in which an obligation arises for the Company or the underwriters to publish a prospectus for such offer.

For the purpose of the above provisions, the expression "an offer to the public" in relation to any share of common stock in any Relevant Member State means the communication in any form and by any means of sufficient information on the terms of the offer and the shares of our common stock to be offered so as to enable an investor to decide to purchase or subscribe the share of our common stock, as the same may be varied in the Relevant Member State by any measure implementing the

Prospectus Directive in the Relevant Member State and the expression "Prospectus Directive" means Directive 2003/71/EC (including the 2010 PD Amending Directive, to the extent implemented in the Relevant Member States) and includes any relevant implementing measure in the Relevant Member State and the expression "2010 PD Amending Directive" means Directive 2010/73/EU.

In addition, in the United Kingdom, this document is being distributed only to, and is directed only at, and any offer subsequently made may only be directed at persons who are "qualified investors" (as defined in the Prospectus Directive) (i) who have professional experience in matters relating to investments falling within Article 19 (5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005, as amended (the "Order") and/or (ii) who are high net worth companies (or persons to whom it may otherwise be lawfully communicated) falling within Article 49(2)(a) to (d) of the Order (all such persons together being referred to as "relevant persons"). This document must not be acted on or relied on in the United Kingdom by persons who are not relevant persons. In the United Kingdom, any investment or investment activity to which this document relates is only available to, and will be engaged in with, relevant persons.

This prospectus supplement does not constitute an issue prospectus pursuant to Article 652a or Article 1156 of the Swiss Code of Obligations and the shares of our common stock will not be listed on the SIX Swiss Exchange. Therefore, this prospectus supplement may not comply with the disclosure standards of the listing rules (including any additional listing rules or prospectus schemes) of the SIX Swiss Exchange. Accordingly, the shares of our common stock may not be offered to the public in or from Switzerland, but only to a selected and limited circle of investors who do not subscribe to the shares of our common stock with a view to distribution. Any such investors will be individually approached by the underwriters from time to time.

This prospectus supplement relates to an Exempt Offer in accordance with the Offered Securities Rules of the Dubai Financial Services Authority ("DFSA"). This prospectus supplement is intended for distribution only to persons of a type specified in the Offered Securities Rules of the DFSA. It must not be delivered to, or relied on by, any other person. The DFSA has no responsibility for reviewing or verifying any documents in connection with Exempt Offers. The DFSA has not approved this prospectus supplement nor taken steps to verify the information set forth herein and has no responsibility for the prospectus supplement. The shares of our common stock to which this prospectus supplement relates may be illiquid and/or subject to restrictions on their resale. Prospective purchasers of the shares of our common stock offered hereby should conduct their own due diligence on the shares of our common stock. If you do not understand the contents of this prospectus supplement you should consult an authorized financial advisor.

The shares of our common stock have not been and will not be registered under the Financial Instruments and Exchange Law of Japan (Law No. 25 of 1948, as amended) and, accordingly, will not be offered or sold, directly or indirectly, in Japan, or for the benefit of any Japanese Person or to others for re-offering or resale, directly or indirectly, in Japan or to any Japanese Person, except in compliance with all applicable laws, regulations and ministerial guidelines promulgated by relevant Japanese governmental or regulatory authorities in effect at the relevant time. For the purposes of this paragraph, "Japanese Person" shall mean any person resident in Japan, including any corporation or other entity organized under the laws of Japan.

This prospectus has not been registered as a prospectus with the Monetary Authority of Singapore. Accordingly, this prospectus and any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of Non-CIS Securities may not be circulated or distributed, nor may the shares of our common stock be offered or sold, or be made the subject of an invitation for subscription or purchase, whether directly or indirectly, to persons in Singapore other than (i) to an institutional investor under Section 274 of the Securities and Futures Act, Chapter 289 of Singapore (the "SFA"), (ii) to a relevant person pursuant to Section 275(1), or any person pursuant to Section 275(1A), and in accordance with the conditions specified in Section 275, of the SFA, or (iii) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA.

Where shares of our common stock are subscribed or purchased under Section 275 of the SFA by a relevant person which is:

securities (as defined in Section 239(1) of the SFA) of that corporation or the beneficiaries' rights and interest (howsoever described) in that trust shall not be transferred within six months after that corporation or that trust has acquired the shares of our common stock pursuant to an offer made under Section 275 of the SFA except:

The shares of our common stock may be sold only to purchasers purchasing, or deemed to be purchasing, as principal that are accredited investors, as defined in National Instrument 45-106 Prospectus Exemptions or subsection 73.3(1) of the Securities Act (Ontario), and are permitted clients, as defined in National Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations. Any resale of the shares of our common stock must be made in accordance with an exemption from, or in a transaction not subject to, the prospectus requirements of applicable securities laws.

Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if this prospectus supplement (including any amendment thereto) contains a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser's province or territory. The purchaser should refer to any applicable provisions of the securities legislation of the purchaser's province or territory for particulars of these rights or consult with a legal advisor.

Pursuant to section 3A.3 of National Instrument 33-105 Underwriting Conflicts (NI 33-105), the underwriters are not required to comply with the disclosure requirements of NI 33-105 regarding underwriter conflicts of interest in connection with this offering.

Certain legal matters in connection with the shares of our common stock will be passed upon by Holland & Hart LLP, as our counsel. Certain legal matters will be passed upon for the underwriters by Baker Botts L.L.P., Dallas, Texas.

The consolidated financial statements of SM Energy Company and subsidiaries as of December 31, 2015 and 2014, and for each of the three years in the period ended December 31, 2015, appearing in SM Energy Company's Annual Report (Form 10-K) for the year ended December 31, 2015, and the effectiveness of SM Energy Company's internal control over financial reporting as of December 31, 2015, have been audited by Ernst & Young LLP, an independent registered public accounting firm, as set forth in their reports thereon, included therein, and incorporated herein by reference. Such consolidated financial statements and SM Energy Company management's assessment of the effectiveness of internal control over financial reporting as of December 31, 2015, are incorporated herein by reference in reliance upon such reports given on the authority of such firm as experts in accounting and auditing.

Certain information with respect to our proved oil and gas reserves referred to and incorporated by reference herein is based in part upon the audit of our proved reserves estimates by Ryder Scott Company, L.P., a firm of independent petroleum engineers. Such information is included and incorporated herein in reliance on the authority of such firm as experts in petroleum engineering.

The oil and natural gas terms defined in this section are used in this prospectus supplement. The definitions of the terms field and proved reserves have been abbreviated from the respective definitions under Rule 4-10(a) of Regulation S-X promulgated by the SEC. The entire definitions of those terms under Rule 4-10(a) of Regulation S-X can be located through the SEC's website at www.sec.gov.

Bbl. One stock tank barrel, or 42 U.S. gallons liquid volume, used in reference to oil or other liquid hydrocarbons.

BOE. Barrels of oil equivalent. Oil equivalents are determined using the ratio of six Mcf of natural gas to one Bbl of oil or NGLs.

BTU. One British thermal unit, the quantity of heat required to raise the temperature of a one-pound mass of water by one degree Fahrenheit.

Field. An area consisting of a single reservoir or multiple reservoirs all grouped on or related to the same individual geological structural feature or stratigraphic condition.

NGLs. The combination of ethane, propane, butane, and natural gasolines that when removed from natural gas become liquid under various levels of higher pressure and lower temperature.

Proved reserves. Those quantities of oil and gas, which, by analysis of geoscience and engineering data, can be estimated with reasonable certainty to be economically producible—from a given date forward, from known reservoirs, and under existing economic conditions, operating methods, and government regulations—prior to the time at which contracts providing the right to operate expire, unless evidence indicates that renewal is reasonably certain, regardless of whether deterministic or probabilistic methods are used for the estimation. Existing economic conditions include prices and costs at which economic producibility from a reservoir is to be determined, and the price to be used is the average price during the 12-month period prior to the ending date of the period covered by the report, determined as an unweighted arithmetic average of the first-day-of-the-month price for each month within such period, unless prices are defined by contractual arrangements, excluding escalations based upon future conditions.

PV-10. The present value of estimated future gross revenue to be generated from the production of estimated net proved reserves, net of estimated production and future development costs, based on prices used in estimating the proved reserves and costs in effect as of the date indicated (unless such costs are subject to change pursuant to contractual provisions), without giving effect to non-property related expenses such as general and administrative expenses, debt service, future income tax expenses, or depreciation, depletion, and amortization, discounted using an annual discount rate of ten percent. While this measure does not include the effect of income taxes as it would in the use of the standardized measure of discounted future net cash flows calculation, it does provide an indicative representation of the relative value of the Company on a comparative basis to other companies and from period to period.

Standardized measure of discounted future net cash flows. The discounted future net cash flows relating to proved reserves based on prices used in estimating the reserves, year-end costs, and statutory tax rates, and a ten percent annual discount rate. The information for this calculation is included in the note regarding disclosures about oil and gas producing activities contained in the Notes to Consolidated Financial Statements incorporated by reference in this prospectus supplement.

By this prospectus, SM Energy Company may offer, from time to time, its common stock and debt securities. We will provide the specific terms of any securities to be offered in a supplement to this prospectus, which may also add, update or change information contained in this prospectus. You should read this prospectus and any supplement carefully before investing.

Our common stock, par value $0.01 per share, is listed on the New York Stock Exchange under the trading symbol "SM." Each prospectus supplement will indicate if the securities offered thereby will be listed on any securities exchange.

Investing in securities involves risks. You should carefully read the risk factors included in the applicable prospectus supplement and in our periodic reports and other information filed with the Securities and Exchange Commission before investing in our securities. See "Risk Factors" beginning on page 4 of this prospectus for information on certain risks related to the purchase of our securities.

We may offer and sell these securities from time to time in amounts, at prices and on terms to be determined by market conditions and other factors at the time of our offerings. We may offer and sell these securities through agents, through underwriters or dealers or directly to one or more purchasers, including existing shareholders. This prospectus provides you with a general description of these securities and the general manner in which we will offer the securities. Each time securities are offered, we will provide a prospectus supplement that will contain specific information about the terms of that offering. This prospectus may not be used to consummate sales of our securities unless it is accompanied by the applicable prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities, or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

This prospectus is part of an "automatic shelf" registration statement on Form S-3 that we filed with the Securities and Exchange Commission (the "SEC") as a "well-known seasoned issuer" as defined under the Securities Act of 1933, as amended (the "Securities Act"). Under the shelf registration process, we may, from time to time, offer and sell in one or more offerings, the securities described in this prospectus.

This prospectus provides you with a general description of the securities we may offer. Each time we sell offered securities, we will provide a prospectus supplement that will contain specific information about the terms of that offering. The prospectus supplement may include additional risk factors or other special considerations applicable to those securities. The prospectus supplement may also add, update or change information contained in this prospectus. If there is any inconsistency between the information in this prospectus and any prospectus supplement, you should rely on the information in the prospectus supplement. You should read both this prospectus and any prospectus supplement and the documents incorporated by reference herein and therein carefully before making your investment decision. You should also read the documents we have referred you to under "Where You Can Find More Information" herein for information about us, including our financial statements.

We have not authorized any dealer, salesman or other person to give any information or to make any representation other than those contained or incorporated by reference in this prospectus and any accompanying prospectus supplement. You must not rely upon any information or representation not contained or incorporated by reference in this prospectus or in any accompanying prospectus supplement. This prospectus and any accompanying prospectus supplement do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the securities to which they relate, nor do this prospectus and any accompanying prospectus supplement constitute an offer to sell or the solicitation of an offer to buy securities in any jurisdiction to any person to whom it is unlawful to make such offer or solicitation in such jurisdiction. You should not assume that the information contained in this prospectus and any accompanying prospectus supplement is accurate on any date subsequent to the date set forth on the front of the document or that any information we have incorporated by reference is correct on any date subsequent to the date of the document incorporated by reference, even though this prospectus and any accompanying prospectus supplement is delivered or securities are sold on a later date.

Unless the context otherwise indicates, the terms "SM Energy," "the Company," "we," "us" and "our" in this prospectus mean SM Energy Company, a Delaware corporation, and its subsidiaries.

We are an independent energy company engaged in the acquisition, exploration, development, and production of crude oil, natural gas, and natural gas liquids (also respectively referred to as "oil," "gas," and "NGLs," respectively, throughout the document) in onshore North America. Our common stock trades on the New York Stock Exchange (the "NYSE") under the ticker symbol "SM."

Our principal offices are located at 1775 Sherman Street, Suite 1200, Denver, Colorado 80203, and our telephone number is (303) 861-8140.

This prospectus contains "forward-looking statements" within the meaning of Section 27A of the Securities Act and Section 21E of the Securities Exchange Act of 1934, as amended (the "Securities Exchange Act"). All statements, other than statements of historical facts, included in this prospectus that address activities, events, or developments with respect to our financial condition, results of operations, or economic performance that we expect, believe, or anticipate will or may occur in the future, or that address plans and objectives of management for future operations, are forward-looking statements. The words "anticipate," "assume," "believe," "budget," "estimate," "expect," "forecast," "intend," "plan," "project," "will," and similar expressions are intended to identify forward-looking statements. Forward-looking statements appear throughout this prospectus, and include statements about such matters as:

We caution you that forward-looking statements are not guarantees of future performance and actual results or performance may be materially different from those expressed or implied in the forward-looking statements. The forward-looking statements in this prospectus speak as of the filing date of this prospectus. Although we may from time to time voluntarily update our prior forward-looking statements, we disclaim any commitment to do so except as required by securities laws.

An investment in our securities involves a significant degree of risk. Before you invest in our securities you should carefully consider those risk factors included in our most recent Annual Report on Form 10-K, any subsequently filed Quarterly Reports on Form 10-Q and any subsequently filed Current Reports on Form 8-K, which are incorporated herein by reference, and those risk factors that may be included in any applicable prospectus supplement, together with all of the other information included in this prospectus, any prospectus supplement and the documents we incorporate by reference, in evaluating an investment in our securities. If any of these risks were actually to occur, our business, financial condition or results of operations could be materially adversely affected. Additional risks not presently known to us or that we currently believe are immaterial may also significantly impair our business operations and financial condition. Please read the information under the caption "Cautionary Statement Regarding Forward-Looking Statements."

Our ratio of earnings to fixed charges for each of the periods indicated is as follows:

Unless otherwise indicated in an accompanying prospectus supplement, we expect to use the net proceeds from the sale of the securities offered by this prospectus for general corporate purposes, which may include, among other things:

The precise amount and timing of the application of such proceeds will depend upon our funding requirements and the availability and cost of other funds.

Our authorized capital stock consists of 200,000,000 shares of capital stock, par value $0.01 per share. As of July 27, 2016, there were 68,466,823 shares of common stock outstanding and no shares of preferred stock outstanding.

Holders of common stock are entitled to one vote for each share held in the election of directors and on all other matters submitted to a vote of stockholders and do not have cumulative voting rights. Holders of a majority of the shares of common stock entitled to vote in any election of directors may elect all of the directors standing for election.

Holders of common stock are entitled to receive ratably such dividends, if any, as may be declared by the Board of Directors out of funds legally available therefor. Upon the liquidation, dissolution or winding up of the Company, the holders of common stock are entitled to receive ratably the net assets of the Company available after payment of all debts and other liabilities. Holders of common stock have no preemptive, subscription, redemption or conversion rights. The outstanding shares of common stock are, and the shares offered by the Company in this offering will be, when issued and paid for, fully paid and non-assessable.

Delaware corporate law and the Company's certificate of incorporation and by-laws contain provisions that may have the effect of delaying or preventing a change of control of the Company or its management. These provisions, among other things, provide for non-cumulative voting in the election of members of the Board of Directors and impose procedural requirements on stockholders who wish to make nominations for the election of directors or propose other actions at stockholder meetings.

The Company's certificate of incorporation provides that authorized but unissued shares of common stock are available for future issuance without stockholder approval, subject to various limitations imposed by the NYSE. These additional shares may be utilized for a variety of corporate purposes, including future public offerings to raise additional capital, corporate acquisitions and employee benefit plans. The existence of authorized but unissued shares of common stock could make it more difficult or discourage an attempt to obtain control of the Company by means of a proxy contest, tender offer, merger or otherwise.

In addition, the Delaware General Corporation Law (the "DGCL"), which applies to the Company as a corporation organized in the State of Delaware, imposes restrictions on business combinations with interested parties. Section 203 of the DGCL, an anti-takeover law, prevents Delaware corporations

under certain circumstances from engaging in a "business combination" with an "interested stockholder" (generally, a holder of 15% or more of the outstanding voting stock of the corporation). A "business combination" includes a merger or sale of 10% or more of a company's assets. However, the provisions of Section 203 do not apply if (1) the board of directors approves the transaction; (2) after the completion of the transaction that resulted in the stockholder becoming an "interested stockholder," that stockholder owned at least 85% of the company's voting stock outstanding at the time the transaction commenced, excluding shares owned by officers and directors and certain employee benefit plans; or (3) on or subsequent to the date of the transaction, the business combination is approved by the board of directors and authorized at a meeting of stockholders by an affirmative vote of at least two-thirds of the outstanding voting stock not owned by the "interested stockholder." These provisions of Delaware law and our certificate of incorporation and by-laws may have the effect of delaying, deferring or preventing a change in control of the Company, even if the change in control might be beneficial to Company stockholders.

Our certificate of incorporation provides that our directors will not be personally liable to us or our stockholders for monetary damages for breach of fiduciary duty as a director, except for liability (1) for any breach of a director's duty of loyalty to the Company or its stockholders, (2) for acts or omissions not in good faith or which involve intentional misconduct or a knowing violation of law, (3) under Section 174 of the Delaware General Corporation Law, or (4) for any transaction from which the director derives an improper personal benefit. If the Delaware General Corporation Law is amended to authorize the further elimination or limitation of directors' liability, then the liability of our directors will automatically be limited to the fullest extent provided by law. Our certificate of incorporation and by-laws also contain provisions to indemnify our directors and officers to the fullest extent permitted by the Delaware General Corporation Law. These provisions and agreements may have the practical effect in certain cases of eliminating the ability of stockholders to collect monetary damages from our directors and officers. We believe that these the provisions in our certificate of incorporation and by-laws are necessary to attract and retain qualified persons as directors and officers.

The transfer agent and registrar for our common stock is Computershare Trust Company N.A.

The following description of the debt securities sets forth certain general terms and provisions of the debt securities to which this prospectus and any prospectus supplement may relate. The particular terms of any series of debt securities and the extent to which the general provisions may apply to a particular series of debt securities will be described in a prospectus supplement relating to that series. References in this section to "SM Energy" mean SM Energy Company and not its subsidiaries.

Any debt securities offered by this prospectus will be issued under an indenture between SM Energy and U.S. Bank National Association, as trustee (the "indenture"), which is incorporated by reference as an exhibit to the registration statement of which this prospectus forms a part. We have summarized selected provisions of the indenture below. You should read the indenture for provisions that may be important to you.

Because we have included only a summary of the indenture terms, you must read the indenture in full to understand every detail of the terms of the debt securities.

The indenture will not limit the amount of debt securities we may issue under it, and will provide that additional debt securities of any series may be issued up to the aggregate principal amount that we authorize from time to time.

Unless otherwise indicated in the applicable prospectus supplement, we will issue the debt securities in denominations of $2,000 and in integral multiples of $1,000 in excess thereof.

Principal and any premium and interest in respect of the debt securities will be payable, and the debt securities will be transferable, at the corporate trust office of the trustee, unless we specify otherwise in the applicable prospectus supplement. At our option, however, we may pay interest by mailing checks to the registered holders of the debt securities at their registered addresses.

We will describe any special U.S. federal income tax and other considerations relating to the debt securities in the applicable prospectus supplement.

The indenture provides that SM Energy may issue separate series of debt securities under the indenture from time to time without limitation as to aggregate principal amount. We may specify a maximum aggregate principal amount for the debt securities of any series. We will determine the terms and conditions of the debt securities, including the maturity, principal and interest, but those terms must be consistent with the indenture. The debt securities will be unsecured obligations of SM Energy.

The prospectus supplement relating to the particular series of debt securities being offered will specify the amounts, prices and terms of those debt securities. These terms may include:

We are not obligated to issue all debt securities of any one series at the same time. The debt securities of any one series may not bear interest at the same rate or mature on the same date.

If we sell any of the debt securities for foreign currencies or foreign currency units or if the principal of, or any premium or interest on, any series of debt securities is payable in foreign currencies or foreign currency units, we will describe the restrictions, elections, tax consequences, specific terms and other information with respect to those debt securities in the applicable prospectus supplement.

Unless otherwise indicated in the applicable prospectus supplement, SM Energy's obligation to pay the principal of, and any premium and interest on, its senior debt securities will be unsecured and will rank equally with all of SM Energy's other unsecured unsubordinated indebtedness.

The debt securities will earn interest at a fixed or floating rate or rates for the period or periods of time specified in the applicable prospectus supplement. Unless otherwise specified in the applicable prospectus supplement, the debt securities will bear interest on the basis of a 360-day year consisting of twelve 30-day months.

We may sell debt securities at a substantial discount below their stated principal amount, bearing no interest or interest at a rate that at the time of issuance is below market rates. We will describe the federal income tax consequences and special considerations that apply to those debt securities in the applicable prospectus supplement.

Unless otherwise specified, debt securities of any series will be exchangeable for other debt securities of the same series and of like aggregate principal amount and tenor in different authorized denominations.

You may present debt securities for registration of transfer, together with a duly executed form of transfer, at the office of the transfer agent designated by us for that purpose with respect to any series of debt securities and referred to in the applicable prospectus supplement. This may be done without service charge but upon payment of any taxes and other governmental charges as described in the indenture. The security registrar or the transfer agent will effect the transfer or exchange upon being satisfied with the documents of title and identity of the person making the request. We may at any time designate additional transfer agents with respect to any series of debt securities.

Unless we specify otherwise in the applicable prospectus supplement, we will pay the principal of, and any premium and interest on, the debt securities at the office of the paying agent or paying agents that we designate at various times. At our option, we may, however, make interest payments by check mailed to the address, as it appears in the security register, of the person entitled to the payments. Unless we specify otherwise in the applicable prospectus supplement, the Corporate Trust Office of the trustee in Denver, Colorado, will be designated as our sole paying agent for payments with respect to debt securities that are issuable solely as registered securities.

All monies we pay to a paying agent for the payment of principal of, and any premium and interest on, any debt security that remains unclaimed at the end of two years after becoming due and payable will be repaid to us. After that time, the holder of the debt security will look only to us for payments out of those repaid amounts.

Some or all of the debt securities of any series may be represented, in whole or in part, by one or more global securities that will have an aggregate principal amount equal to that of the debt securities they represent. Each global security will be registered in the name of a depositary or its nominee identified in the applicable prospectus supplement, will be deposited with such depositary or nominee or its custodian and will bear a legend regarding the restrictions on exchanges and registration of transfer thereof referred to below and any such other matters as may be provided for pursuant to the indenture.

Unless otherwise specified in the applicable prospectus supplement, any one of the following events will constitute an "event of default" under the indenture with respect to the debt securities of any series issued under the indenture:

If we fail to pay the principal of, or premium, if any, or interest on, the debt securities of any series or we fail to perform or breach any of the other covenants or warranties applicable to the debt securities of that series, and such event of default is continuing, the holders of not less than 25% in aggregate principal amount of the outstanding debt securities of that series (or with respect to covenant and warranty defaults, the holders of not less than a majority in aggregate principal amount of the outstanding debt securities of that series) may declare the principal amount of, and any premium and

interest on, the debt securities of that series to be due and payable immediately. If an event of default occurs involving certain events of bankruptcy, insolvency or reorganization, and the event of default is continuing, then the principal amount of all of the debt securities of such series then outstanding under the indenture will become due and payable immediately, without notice or other action by any holder or the trustee, to the full extent permitted by law. At any time after a declaration of acceleration has been made, but before a judgment or decree for payment of money has been obtained by the trustee, the holders of not less than a majority in aggregate principal amount of the debt securities of any series may rescind and annul any declaration of acceleration with respect to such series of debt securities if we deposit with the trustee an amount sufficient to pay all overdue interest on the debt securities of that series, the principal of and premium, if any, on the debt securities of that series that have become due and payable otherwise than by such declaration of acceleration and all amounts due to the trustee and if all other events of default with respect to the debt securities of that series have been cured or waived.

Within 90 days after the occurrence of any event of default under the indenture with respect to the debt securities of any series issued under the indenture, the trustee must transmit notice of the event of default to the holders of the debt securities of that series unless the event of default has been cured or waived. The trustee may withhold the notice, however, except in the case of a payment default, if and so long as the board of directors, the executive committee or a trust committee of directors or responsible officers of the trustee has in good faith determined that the withholding of the notice is in the interest of the holders of debt securities of that series.

If an event of default occurs and is continuing with respect to the debt securities of any series, the trustee may in its discretion proceed to protect and enforce its rights and the rights of the holders of debt securities of that series by all appropriate judicial proceedings.

Subject to the duty of the trustee during any default to act with the required standard of care, the trustee is under no obligation to exercise any of its rights or powers under the indenture at the request or direction of any of the holders of debt securities issued under the indenture, unless the holders offer the trustee reasonable indemnity. Subject to indemnifying the trustee, and subject to applicable law and certain other provisions of the indenture, the holders of not less than a majority in aggregate principal amount of the outstanding debt securities of a series issued under the indenture may direct the time, method and place of conducting any proceeding for any remedy available to the trustee, or exercising any trust or power conferred on the trustee, with respect to the debt securities of that series.

Unless the applicable prospectus supplement provides otherwise, any debt securities, or portion of the principal amount of the debt securities, will be deemed to have been paid for purposes of the indenture, and, at our election, our entire indebtedness with respect to the debt securities, or portion thereof, will be deemed to have been satisfied and discharged, if we have irrevocably deposited with the trustee or any paying agent other than us, in trust, money, certain eligible obligations, as defined in the indenture, or a combination of the two, sufficient to pay principal of and any premium and interest due and to become due on the debt securities or portions thereof, and have met certain other conditions set forth in the indenture.

In addition, unless the applicable prospectus supplement provides otherwise, we shall be released from our obligations under certain covenants set forth in the indenture (or certain additional covenants applicable to a particular series of debt securities) if we have irrevocably deposited with the trustee or any paying agent other than us, in trust, money, certain eligible obligations, as defined in the indenture, or a combination of the two, sufficient to pay principal of and any premium and interest due and to become due on the debt securities or portions thereof, and have met certain other conditions set forth in the indenture.

The trustee and SM Energy may, without the consent of holders, modify or waive provisions of the indenture for certain purposes, including, among other things, curing ambiguities and maintaining the qualification of the indenture under the Trust Indenture Act of 1939, as amended. The trustee and SM Energy may modify or waive certain provisions of the indenture with the consent of the holders of not less than a majority in aggregate principal amount of the debt securities of each series issued under the indenture affected by the modification or waiver. The provisions of the indenture may not, however, be waived or modified without the consent of each holder of each debt security of the series affected thereby if the modification or waiver would:

The holders of not less than a majority in aggregate principal amount of outstanding debt securities of any series issued under the indenture may, on behalf of the holders of all debt securities of that series, waive our compliance with certain restrictive provisions of the indenture. The holders of not less than a majority in aggregate principal amount of debt securities of any series issued under the indenture may, on behalf of all holders of debt securities of that series, waive any past default and its consequences under the indenture with respect to the debt securities of that series, except:

We may not consolidate with or merge with or into, or sell, assign, transfer, lease or convey or otherwise dispose of all or substantially all of our assets and properties and the assets and properties or our subsidiaries (taken as a whole) in one or more related transactions to any person (as defined in the indenture) unless:

The indenture and the debt securities will be governed by, and construed in accordance with, the laws of the State of New York. The indenture is subject to the provisions of the Trust Indenture Act that are required to be part of the indenture and will, to the extent applicable, be governed by those provisions.

We may appoint a separate trustee for any series of debt securities. In the description of a series of debt securities, the term "trustee" refers to the trustee appointed with respect to such series of debt securities. The trustee may be a depository for funds and perform other services for, and may transact other banking business with, SM Energy and its subsidiaries in the normal course of business.

Unless otherwise specified in the applicable prospectus supplement, we will issue securities, other than our common stock, to investors in the form of one or more book-entry certificates registered in the name of a depository or a nominee of a depository. Unless otherwise specified in the applicable prospectus supplement, the depository will be DTC. We have been informed by DTC that its nominee will be Cede & Co., or Cede. Accordingly, Cede is expected to be the initial registered holder of all securities that are issued in book-entry form.

No person that acquires a beneficial interest in securities issued in book-entry form will be entitled to receive a certificate representing those securities, except as set forth in this prospectus or in the applicable prospectus supplement. Unless and until definitive securities are issued under the limited circumstances described below, all references to actions by holders or beneficial owners of securities issued in book-entry form will refer to actions taken by DTC upon instructions from its participants, and all references to payments and notices to holders or beneficial owners will refer to payments and notices to DTC or Cede, as the registered holder of such securities.

Participants have accounts with DTC and include securities brokers and dealers, banks, trust companies and clearing corporations. Indirect access to the DTC system also is available to indirect participants such as banks, brokers, dealers and trust companies that clear through or maintain a custodial relationship with a participant, either directly or indirectly.

Persons that are not participants or indirect participants but desire to buy, sell or otherwise transfer ownership of or interests in securities may do so only through participants and indirect participants. Under the book-entry system, beneficial owners may experience some delay in receiving payments, as payments will be forwarded by our agent to Cede, as nominee for DTC. These payments will be forwarded to DTC's participants, which thereafter will forward them to indirect participants or beneficial owners. Beneficial owners will not be recognized by the applicable registrar, transfer agent, trustee or depositary as registered holders of the securities entitled to the benefits of the certificate, the indenture or any deposit agreement. Beneficial owners that are not participants will be permitted to exercise their rights as an owner only indirectly through participants and, if applicable, indirect participants.

Under the current rules and regulations affecting DTC, DTC will be required to make book-entry transfers of securities among participants and to receive and transmit payments to participants. Participants and indirect participants with whom beneficial owners of securities have accounts are also required by these rules to make book-entry transfers and receive and transmit such payments on behalf of their respective account holders.

Because DTC can act only on behalf of participants, who in turn act only on behalf of other participants or indirect participants, and on behalf of certain banks, trust companies and other persons approved by it, the ability of a beneficial owner of securities issued in book-entry form to pledge those securities to persons or entities that do not participate in the DTC system may be limited due to the unavailability of physical certificates for the securities.

DTC has advised us that it will take any action permitted to be taken by a registered holder of any securities under the certificate, the indenture or any deposit agreement only at the direction of one or more participants to whose accounts with DTC the securities are credited.

According to DTC, it has provided information with respect to DTC to its participants and other members of the financial community for informational purposes only and is not intended to serve as a representation, warranty or contract modification of any kind.

Unless otherwise specified in the applicable prospectus supplement, a book-entry security will be exchangeable for definitive securities registered in the names of persons other than DTC or its nominee only if:

Any book-entry security that is exchangeable in accordance with the preceding sentence will be exchangeable for securities registered in such names as DTC directs.

If one of the events described in the immediately preceding paragraph occurs, DTC is generally required to notify all participants of the availability through DTC of definitive securities. Upon surrender by DTC of the book-entry security representing the securities and delivery of instructions for re-registration, the registrar, transfer agent, trustee or depositary, as the case may be, will reissue the securities as definitive securities. After reissuance of the securities, such persons will recognize the beneficial owners of such definitive securities as registered holders of securities.

None of SM Energy, the trustee, any registrar and transfer agent or any depository, or any agent of any of them, will have any responsibility or liability for any aspect of DTC's or any participant's records relating to, or for payments made on account of, beneficial interests in a book-entry security.

We may sell the securities pursuant to this prospectus and any accompanying prospectus supplement:

We will prepare a prospectus supplement for each offering that will disclose the terms of the offering, including the name or names of any underwriters, dealers or agents, the purchase price of the securities and the proceeds to us from the sale, any underwriting discounts and other items constituting compensation to underwriters, dealers or agents and any delayed delivery arrangements.

The distribution of the securities may be effected from time to time in one or more transactions at a fixed price, at prevailing market prices at the time of the sale, at prices related to such prevailing market prices at varying prices determined at the time of sale, or at negotiated prices.

Securities offered by us pursuant to this prospectus may be sold through agents designated by us. Unless otherwise indicated in the prospectus supplement, any such agent is acting on a best efforts basis for the period of its appointment.

If underwriters are used in the sale, the offered securities will be acquired by the underwriters for their own account. The underwriters may resell the securities in one or more transactions, including negotiated transactions, at a fixed public offering price or at varying prices determined at the time of sale. The obligations of the underwriters to purchase the securities will be subject to certain conditions. Unless otherwise indicated in the prospectus supplement, the underwriters must purchase all the securities of the series offered by a prospectus supplement if any of the securities are purchased. Any initial public offering price and any discounts or concessions allowed or re-allowed or paid to dealers may be changed from time to time.

Securities offered by us pursuant to this prospectus may also be sold directly by us. In this case, no underwriters or agents would be involved. We may sell the securities directly to institutional investors or others who may be deemed to be underwriters within the meaning of the Securities Act, with respect to any sale of those securities. We will describe the terms of any such sales in the prospectus supplement.

We may authorize agents, underwriters or dealers to solicit offers by certain institutional investors to purchase offered securities providing for payment and delivery on a future date specified in the prospectus supplement. Institutional investors to which such offers may be made, when authorized, include commercial and savings banks, insurance companies, pension funds, investment companies, education and charitable institutions and such other institutions as may be approved by us. The obligations of any such purchasers under such delayed delivery and payment arrangements will be subject to the condition that the purchase of the offered securities will not at the time of delivery be prohibited under applicable law. The underwriters and such agents will not have any responsibility with respect to the validity or performance of such contracts.

Underwriters, dealers and agents that participate in the distribution of the offered securities may be underwriters as defined in the Securities Act, and any discounts or commissions received by them from us and any profit on the resale of the offered securities by them may be treated as underwriting discounts and commissions under the Securities Act. Any underwriters or agents will be identified and their compensation described in the applicable prospectus supplement.

The securities (other than common stock) offered by this prospectus and any prospectus supplement, when first issued, will have no established trading market. Any underwriters or agents to or through whom such securities are sold by us for public offering and sale may make a market in such securities, but such underwriters or agents will not be obligated to do so and may discontinue any market making at any time without notice. We cannot assure you as to the liquidity of the trading market for any such securities.

We may have agreements with the underwriters, dealers and agents to indemnify them against certain civil liabilities, including liabilities under the Securities Act, or to contribute with respect to payments that the underwriters, dealers or agents may be required to make.

Underwriters, dealers and agents may engage in transactions with, or perform services for, us or our subsidiaries in the ordinary course of their businesses.

In connection with offerings of securities under the registration statement of which this prospectus forms a part and in compliance with applicable law, underwriters, brokers or dealers may engage in transactions that stabilize or maintain the market price of the securities at levels above those that might otherwise prevail in the open market. Specifically, underwriters, brokers or dealers may over-allot in connection with offerings, creating a short position in the securities for their own accounts. For the purpose of covering a syndicate short position or stabilizing the price of the securities, the underwriters, brokers or dealers may place bids for the securities or effect purchases of the securities in the open market. Finally, the underwriters may impose a penalty whereby selling concessions allowed to syndicate members or other brokers or dealers for distribution of the securities in offerings may be reclaimed by the syndicate if the syndicate repurchases previously distributed securities in transactions to cover short positions, in stabilization transactions or otherwise. These activities may stabilize, maintain or otherwise affect the market price of the securities, which may be higher than the price that might otherwise prevail in the open market, and, if commenced, may be discontinued at any time.

Certain legal matters in connection with the securities will be passed upon for us by Holland & Hart LLP or by legal counsel named in the prospectus supplement and for any underwriters by legal counsel named in the prospectus supplement.

Certain information with respect to our proved oil and gas reserves referred to and incorporated by reference herein is based in part upon the audit of our proved reserve estimates by Ryder Scott Company, L.P., a firm of independent petroleum engineers. Such information is included and incorporated herein in reliance on the authority of such firm as experts in petroleum engineering.

We are subject to the informational requirements of the Securities Exchange Act, and we file annual, quarterly and other reports and other information with the SEC. You may read and copy any document we file with the SEC at the SEC's public reference room at 100 F Street NE, Washington, D.C. 20549-2521. Please call 1-800-732-0330 for further information concerning the operation of the public reference room. Our SEC filings are also available on the SEC's web site at http://www.sec.gov. Unless specifically listed under "Incorporation by Reference" below, the information contained on the

SEC web site is not intended to be incorporated by reference in this prospectus and you should not consider that information a part of this prospectus.

Our common stock is listed and traded on the NYSE. Our reports, proxy statements and other information filed with the SEC can also be inspected and copied at the NYSE, 20 Broad Street, New York, New York 10005.

We make available free of charge on or through our Internet website, http://www.sm-energy.com, our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Securities Exchange Act as soon as reasonably practicable after we electronically file such material with, or furnish it to, the SEC. Information contained on our Internet website is not part of this prospectus and does not constitute a part of this prospectus.

This prospectus incorporates important business and financial information about us that is not included in or delivered with this prospectus. We will provide this information and any and all of the documents referred to herein, including the indenture for the notes, which is summarized in this prospectus, without charge to each person to whom a copy of this prospectus has been delivered, who makes a written or oral request at the following address or telephone number:

Investor Relations
SM Energy Company
1775 Sherman Street, Suite 1200
Denver, Colorado 80203
(303) 861-8140
information@sm-energy.com

We "incorporate by reference" in this prospectus certain documents that we have previously filed with the SEC. This means that we are disclosing important information to you without actually including that information in this prospectus by referring you to other documents that we have filed separately with the SEC. The information incorporated by reference is an important part of this prospectus. Information that we later provide to the SEC, and which is deemed "filed" with the SEC, will automatically update information that we previously filed with the SEC, and may replace information in this prospectus and information that we previously filed with the SEC. We incorporate by reference the following documents in this prospectus, which you should review in connection with this prospectus:

We also incorporate by reference each of the documents that we file with the SEC (excluding any portion of those filings furnished under Items 2.02 or 7.01 of Form 8-K or other information furnished to the SEC) under Sections 13(a), 13(c), 14, or 15(d) of the Securities Exchange Act on or after this

registration statement. Any statements made in such documents will automatically update and supersede the information contained in this prospectus, and any statements made in this prospectus update and supersede the information contained in past SEC filings incorporated by reference into this prospectus.

You should rely only on the information contained or incorporated by reference in this prospectus, any applicable prospectus supplement, or any free writing prospectus we may authorize to be delivered to you. You should not assume that the information incorporated by reference or provided in this prospectus, any applicable prospectus supplement or any free writing prospectus is accurate as of any date other than the date on the front of each document.

Wells Fargo Securities
BofA Merrill Lynch
J.P. Morgan
Barclays
BBVA
RBC Capital Markets

	Per Share	Total




Public offering price	$	$

Underwriting discount and commissions	$	$

Proceeds, before expenses, to us	$	$


Wells Fargo Securities	BofA Merrill Lynch	J.P. Morgan
Barclays	BBVA	RBC Capital Markets

		Page

About this Prospectus Supplement and the Accompanying Prospectus			S-ii
Where You Can Find More Information			S-ii
Incorporation by Reference			S-iii
Cautionary Statement Regarding Forward-Looking Statements			S-iii
Prospectus Supplement Summary			S-1
The Offering			S-4
Summary Consolidated Historical Financial Information			S-5
Summary Reserve, Production and Operating Data			S-10
Risk Factors			S-14
Use of Proceeds			S-19
Capitalization			S-20
Price Range of Common Stock			S-22
Dividend Policy			S-22
Material U.S. Federal Income Tax Considerations for Non-U.S. Holders			S-23
Certain ERISA Considerations			S-27
Underwriting			S-29
Legal Matters			S-37
Experts			S-37
Glossary of Oil and Natural Gas Terms			S-37

		Page

About This Prospectus			1
SM Energy Company			1
Cautionary Statement Regarding Forward Looking Statements			2
Risk Factors			4
Ratio of Earnings to Fixed Charges			4
Use of Proceeds			5
Description of Capital Stock			5
Description of Debt Securities			6
Book-entry Securities			12
Plan of Distribution			14
Legal Matters			16
Experts			16
Where You Can Find More Information			16
Incorporation by Reference			17

	No Exercise	Full Exercise

Per share	$	$
Total	$	$

	Six Months Ended June 30, 2016	Year Ended December 31,

	Six Months Ended June 30, 2016	2015	2014	2013	2012	2011
Ratio of earnings to fixed charges(1)	—(2)	—(3)	10.0x	3.7x	—(4)	6.7x