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(a)   Intersegment revenues primarily represent natural gas sales from EQT Production to EQT Midstream and transportation activities between EQT Midstream and Distribution.

(b)   Unallocated (expenses) income consists primarily of incentive compensation and administrative costs that are not allocated to the operating segments.

(c)    Expenditures for segment assets for 2007 include $24.4 million and $3.7 million, in the EQT Production and EQT Midstream segments, respectively, for the acquisition of additional working interest and related gathering assets in the Roaring Fork area. Expenditures for segment assets in the EQT Production segment include $85.5 million and $31.0 million for undeveloped property acquisitions in 2008 and 2009, respectively.

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Risk factors

Any investment in our common stock involves a high degree of risk. You should carefully consider the risks described below and all of the information contained in this prospectus supplement and the accompanying prospectus before deciding whether to purchase our common stock. In addition, you should carefully consider, among other things, the matters discussed under "Risk factors" in our Annual Report on Form 10-K for the fiscal year ended December 31, 2009, and in other documents that we subsequently file with the Securities and Exchange Commission, all of which are incorporated by reference to the prospectus accompanying this prospectus supplement. The risks and uncertainties described below are not the only risks and uncertainties we face. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also impair our business operations. If any of the following risks actually occur, our business, financial condition and results of operations would suffer. In that event, the trading price of our common stock could decline, and you may lose all or part of your investment in our common stock. The risks discussed below also include forward-looking statements and our actual results may differ substantially from those discussed in these forward-looking statements. See "Cautionary statements."

Risks related to this offering

Future sales of our common stock in the public market or the issuance of securities senior to our common stock could adversely affect the trading price of our common stock and our ability to raise funds in new stock offerings.

Sales by us or our shareholders of a substantial number of shares of our common stock in the public markets following this offering, or the perception that these sales might occur, could cause the market price of our common stock to decline or could impair our ability to raise capital through a future sale of, or pay for acquisitions using, our equity securities.

We and certain of our executive officers will agree, with limited exceptions, for a period of 90 days after the date of this prospectus supplement, that we and they will not, without the prior written consent of the representatives on behalf of the underwriters, directly or indirectly, offer to sell, sell or otherwise dispose of any shares of our common stock. All of the shares sold in this offering will be freely transferable, except for any shares sold to our "affiliates," as that term is defined in Rule 144 under the Securities Act of 1933, as amended, or Securities Act.

We may issue common stock or equity securities senior to our common stock in the future for a number of reasons, including to finance our operations and growth plans, to adjust our ratio of debt-to-equity, to satisfy our obligations upon the exercise of options or for other reasons. We cannot predict the effect, if any, that future sales or issuance of shares of our common stock or other equity securities, or the availability of shares of common stock or such other equity securities for future sale or issuance, will have on the trading price of our common stock.

The price of our common stock may fluctuate significantly, which could negatively affect us and holders of our common stock.

The trading price of our common stock may fluctuate significantly in response to a number of factors, many of which are beyond our control. For instance, if our financial results are below

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the expectations of securities analysts and investors, the market price of our common stock could decrease, perhaps significantly. Other factors that may affect the market price of our common stock include announcements relating to significant corporate transactions; fluctuations in our quarterly and annual financial results; operating and stock price performance of companies that investors deem comparable to us; and changes in government regulation or proposals relating to us. In addition, the U.S. securities markets have experienced significant price and volume fluctuations. These fluctuations often have been unrelated to the operating performance of companies in these markets. Market fluctuations and broad market, economic and industry factors may negatively affect the price of our common stock, regardless of our operating performance. You may not be able to sell your shares of our common stock at or above the public offering price, or at all. Any volatility of or a significant decrease in the market price of our common stock could also negatively affect our ability to make acquisitions using common stock. Further, if we were to be the object of securities class action litigation as a result of volatility in our common stock price or for other reasons, it could result in substantial costs and diversion of our management's attention and resources, which could negatively affect our financial results.

The issuance of additional stock in connection with acquisitions or otherwise will dilute all other stockholdings.

After this offering, we will have an aggregate of 149,869,528 shares of common stock authorized but unissued. Subject to certain volume limitations imposed by the New York Stock Exchange, we may issue all of these shares without any action or approval by our shareholders. We intend to continue to actively seek to expand our business through complementary or strategic acquisitions of other companies and assets, and we may issue shares of common stock in connection with those acquisitions. For example, we intend to use shares of our common stock to fund the Marcellus Shale Transaction. Any shares issued in connection with these activities, the exercise of stock options or otherwise would dilute the percentage ownership held by the investors who purchase our shares in this offering.

Our ability to make dividend payments on our common stock depends to a large extent on our ability to receive dividends or other distributions from our subsidiaries.

Our operations are conducted primarily through direct and indirect subsidiaries. We own no significant assets other than our equity in our subsidiaries, and our ability to meet our obligations will be dependent on dividends and other distributions or payments from our subsidiaries. The ability of our subsidiaries to pay dividends or make distributions or other payments to us depends upon the availability of cash flow from operations, proceeds from the sale of assets and/or borrowings, and, in the case of non-wholly owned subsidiaries, our contractual arrangements with other equity holders. In the event of bankruptcy proceedings affecting one of these subsidiaries, to the extent we are recognized as a creditor of that entity, our claim could still be junior to any security interest in or other lien on any assets of that entity and to any of its debt and other obligations. We cannot be certain of the future availability of such distributions and the lack of any such distributions may adversely affect our ability to pay dividends on our common stock.

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Cautionary statements

Our finding and development costs are calculated from the production cost and reserve information provided in Footnote 22 to the consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2009 as costs of oil and gas producing activities divided by changes in reserves excluding production. We expect that additional costs will be required to bring proved undeveloped reserves to production. We provide an estimate of future development costs under the standard measure of discounted cash flows in Footnote 22. We believe that finding and development costs is an important analytical measure used within our industry by investors and peers to evaluate, among other things, the profitability of drilling programs. However, there are limitations as to the usefulness of this measure. For instance, this measure may not be calculated consistently across the industry.

Total sales volumes per day at period end is an operational estimate of the daily sales volume on a typical day (excluding curtailments) at the end of the applicable period.

Disclosures in this prospectus supplement and the documents incorporated by reference herein contain certain forward-looking statements within the meaning of Section 21E of the Securities Exchange Act of 1934, as amended, and Section 27A of the Securities Act of 1933, as amended. Statements that do not relate strictly to historical or current facts are forward-looking and usually identified by the use of words such as "anticipate," "estimate," "forecasts," "approximate," "expect," "project," "intend," "plan," "believe," "will," "may" and other words of similar meaning in connection with any discussion of future operating or financial matters. Without limiting the generality of the foregoing, forward-looking statements contained in this prospectus supplement and the documents incorporated by reference herein include the matters discussed in the section captioned "Outlook" in Management's Discussion and Analysis of Financial Condition and Results of Operations of our Annual Report on Form 10-K for the fiscal year ended December 31, 2009 and our expectations of plans, strategies, objectives and growth and anticipated financial and operational performance, including guidance regarding our drilling and infrastructure programs (including the Equitrans Marcellus Expansion Project) and technology, the estimated number of acres to be held in the high-pressure Marcellus fairway following and the timing of the closing of the Marcellus Shale Transaction, production and sales volumes and growth rates, reserves, finding and development costs, unit costs, capital expenditures and financing requirements. These statements involve risks and uncertainties that could cause actual results to differ materially from projected results. Accordingly, investors should not place undue reliance on forward-looking statements as a prediction of actual results. We have based these forward-looking statements on current expectations and assumptions about future events. While we consider these expectations and assumptions to be reasonable, they are inherently subject to significant business, economic, competitive, regulatory and other risks and uncertainties, most of which are difficult to predict and many of which are beyond our control. The risks and uncertainties that may affect our operations, performance and results and the forward-looking statements include, but are not limited to, those set forth under Item 1A, "Risk factors" of our Annual Report on Form 10-K for the fiscal year ended December 31, 2009.

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Use of proceeds

We estimate that the net proceeds from this offering, after deducting underwriters' discounts and estimated offering expenses of approximately $22,265,000, will be approximately $527,735,000 (or approximately $606,935,000 if the underwriters exercise their overallotment option in full). We intend to use the net proceeds from this offering to accelerate our natural gas drilling and development projects in the Huron/Berea and Marcellus plays and for associated infrastructure projects.

Dividend policy

We paid a quarterly cash dividend of $0.22 per share of common stock on March 1, 2010. The amount and timing of dividends is subject to the discretion of our board of directors and depends on certain business conditions, such as our lines of business, results of operations and financial condition and other factors. Based on currently foreseeable conditions, we anticipate that comparable dividends will be paid on a regular quarterly basis.

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Capitalization

The following table sets forth our cash and cash equivalents and our capitalization as of December 31, 2009 on a historical basis and as adjusted to give effect to this offering and the application of the net proceeds of this offering as described under "Use of proceeds." This table should be read in conjunction with "Management's discussion and analysis of financial condition and results of operations" and the consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2009, which is incorporated by reference in the prospectus accompanying this prospectus supplement.

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Certain United States federal income tax considerations
for non-United States holders

The following is a general discussion of the principal United States federal income tax consequences of the acquisition, ownership and disposition of our common stock by a non-U.S. holder. As used in this discussion, the term "non-U.S. holder" generally means a beneficial owner of our common stock that is not, for U.S. federal income tax purposes:

•

an individual citizen or resident of the United States;

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a corporation or partnership created or organized in or under the laws of the United States, any state thereof or the District of Columbia,

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an estate, the income of which is includible in gross income for U.S. federal income tax purposes regardless of its source; or

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a trust, (a) if a U.S. court is able to exercise primary supervision over the administration of the trust and one or more U.S. persons, within the meaning of section 7701(a)(30) of the Internal Revenue Code of 1986, as amended (the "Code"), have authority to control all substantial decisions of the trust, or (b) that has in effect a valid election under applicable Treasury regulations to be treated as a U.S. person.

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

This discussion does not consider:

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U.S. state, local or non-U.S. income tax consequences;

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estate, gift or other non-income tax consequences;

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special tax rules that may apply to particular non-U.S. holders, such as financial institutions, insurance companies, tax-exempt organizations, U.S. expatriates, broker-dealers and traders in securities; or

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special tax rules that may apply to a non-U.S. holder that holds our common stock as part of a "straddle," "hedge," "conversion transaction," "synthetic security" or other integrated investment.

The following discussion is based on provisions of the Code, the U.S. Treasury regulations promulgated thereunder, and administrative and judicial interpretations, all as in effect on the date of this prospectus supplement, and all of which are subject to change, retroactively or prospectively. The following discussion also assumes that a non-U.S. holder holds our common stock as a capital asset within the meaning of section 1221 of the Code.

EACH NON-U.S. HOLDER SHOULD CONSULT ITS TAX ADVISOR REGARDING THE U.S. FEDERAL, STATE, LOCAL, AND NON-U.S. TAX CONSEQUENCES OF ACQUIRING, HOLDING AND DISPOSING OF SHARES OF OUR COMMON STOCK.

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Dividends

Subject to the discussion below regarding dividends that are effectively connected with a trade or business in the United States, dividends paid with respect to our common stock generally will be subject to U.S. federal withholding tax at a 30% rate on the gross amount of the dividend, or such lower rate as may be provided by an applicable income tax treaty, provided that the non-U.S. holder furnishes proper certification of the applicability of such income tax treaty.

Non-U.S. holders should consult their tax advisors regarding their entitlement to benefits under an applicable income tax treaty and the manner of claiming the benefits of such treaty. A non-U.S. holder that is eligible for a reduced rate of U.S. federal withholding tax under an income tax treaty may obtain a refund or credit of any excess amounts withheld by timely filing an appropriate claim for a refund with the Internal Revenue Service (the "IRS").

Dividends that are effectively connected with a non-U.S. holder's conduct of a trade or business in the United States and, if an income tax treaty applies, that are attributable to a permanent establishment maintained by the non-U.S. holder in the United States, will not be subject to U.S. federal withholding tax, assuming that the non-U.S. holder complies with applicable certification and disclosure requirements, but instead will be taxed in the manner applicable to U.S. persons. In addition, dividends received by a corporate non-U.S. holder that are effectively connected with the conduct of a trade or business in the United States may be subject to a branch profits tax at a 30% rate, or at a lower rate if provided by an applicable income tax treaty.

Gain on disposition of common stock

A non-U.S. holder generally will not be taxed on gain recognized on a disposition of our common stock unless:

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the non-U.S. holder is an individual who holds our common stock as a capital asset, is present in the United States for 183 days or more during the taxable year of the disposition and meets certain other conditions;

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the gain is effectively connected with the non-U.S. holder's conduct of a trade or business in the United States and, if an income tax treaty applies, is attributable to a permanent establishment maintained by the non-U.S. holder in the United States; or

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we are or have been a "U.S. real property holding corporation" for U.S. federal income tax purposes at any time during the shorter of the five-year period ending on the date of disposition or the period that the non-U.S. holder held our common stock, and the non-U.S. holder owns or owned, at any time during the shorter of such periods, more than 5 percent of our common stock.

We believe that we are a U.S. real property holding corporation.

An individual non-U.S. holder who is subject to U.S. tax because such holder was present in the United States for 183 days or more during the year of disposition generally will be taxed on such holder's gain from the disposition of our common stock at a flat rate of 30% (net of any U.S.-source capital loss recognized in such year). Other non-U.S. holders subject to U.S. federal

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income tax on the disposition of our common stock generally will be taxed on such disposition in the same manner in which citizens or residents of the United States would be taxed. In addition, gain recognized by a corporate non-U.S. holder that is effectively connected with the non-U.S. holder's conduct of a trade or business in the United States (and, if an income tax treaty applies, that is attributable to a permanent establishment maintained by the non-U.S. holder in the United States) may be subject to a branch profits tax at a 30% rate, or at a lower rate if provided by an applicable income tax treaty.

Information reporting and backup withholding

In general, backup withholding will not apply to dividends paid on our common stock to a non-U.S. holder if the non-U.S. holder has timely and accurately provided the required certification that it is a non-U.S. holder (and neither we nor our paying agents have actual knowledge or reason to know that the holder is a U.S. person, within the meaning of section 7701(a)(30) of the Code), or the non-U.S. holder otherwise establishes an exemption from backup withholding. Generally, we must report to the IRS the amount of dividends paid to a non-U.S. holder, the name and address of the recipient, and the amount, if any, of tax withheld. These information reporting requirements apply even if no tax was required to be withheld. A similar report is sent to the recipient of the dividends. Copies of the information returns reporting such dividends may also be made available to the tax authorities in the country in which the non-U.S. holder resides under the provisions of an applicable income tax treaty.

In general, backup withholding and information reporting will not apply to proceeds from the disposition of common stock paid to a non-U.S. holder if the holder has timely and accurately provided any required certification that it is a non-U.S. holder (and the payor does not have actual knowledge or reason to know that the holder is a U.S. person, within the meaning of section 7701(a)(30) of the Code), or the non-U.S. holder otherwise establishes an exemption from backup withholding and information reporting. Such certification is generally required if the disposition of common stock is conducted within the United States or through certain United States-related financial intermediaries.

Any amounts withheld under the backup withholding rules from a payment to a non-U.S. holder will be credited against the holder's U.S. federal income tax liability, if any, and may entitle the holder to a refund, provided that certain required information is timely and accurately furnished to the IRS.

Recently proposed legislation would generally impose, effective for payments made after December 31, 2012, a withholding tax of 30% on dividends from, and the gross proceeds of a disposition of, common stock paid to certain foreign entities unless various information reporting requirements are satisfied. A substantially similar proposal was included as part of a proposed U.S. federal budget for the fiscal year 2011. There can be no assurance as to whether or not this proposed legislation (or any substantially similar legislation) will be enacted, and, if it is enacted, what form it will take or when it will be effective. Non-U.S. holders are encouraged to consult their own tax advisors regarding the possible implications of this proposed legislation on their investment in our common stock.

NON-U.S. HOLDERS SHOULD CONSULT THEIR TAX ADVISORS REGARDING THE APPLICATION OF THE INFORMATION REPORTING AND BACKUP WITHHOLDING RULES TO THEM.

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Underwriting

We are offering the shares of common stock described in this prospectus supplement through a number of underwriters. J.P. Morgan Securities Inc., Barclays Capital Inc., Credit Suisse Securities (USA) LLC and Deutsche Bank Securities Inc. are acting as joint book-running managers of the offering and as representatives of the underwriters. We have entered into an underwriting agreement with the underwriters. Subject to the terms and conditions of the underwriting agreement, we have agreed to sell to the underwriters, and each underwriter has severally agreed to purchase, at the public offering price less the underwriting discounts and commissions set forth on the cover page of this prospectus supplement, the number of shares of common stock listed next to its name in the following table:

The underwriters are committed to purchase all the common shares offered by us if they purchase any shares. The underwriting agreement also provides that if an underwriter defaults, the purchase commitments of non-defaulting underwriters may also be increased or the offering may be terminated.

The underwriters propose to offer the common shares directly to the public at the public offering price set forth on the cover page 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 $1.056 per share. After the public offering of the shares, the offering price and other selling terms may be changed by the underwriters.

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The underwriters have an option to buy up to 1,875,000 additional shares of common stock from us. The underwriters have 30 days from the date of this prospectus supplement to exercise this option. If any shares are purchased with this option, the underwriters will purchase shares in approximately the same proportion as shown in the table above. If any additional shares of common stock are purchased, the underwriters will offer the additional shares on the same terms as those on which the shares are being offered.

The underwriting fee is equal to the public offering price per share of common stock less the amount paid by the underwriters to us per share of common stock. The underwriting fee is $1.76 per share. The following table shows the per share and total underwriting discounts and commissions to be paid to the underwriters assuming both no exercise and full exercise of the underwriters' option to purchase additional shares.

We estimate that the total expenses of this offering, excluding underwriting discounts and commissions, will be approximately $265,000.

We have agreed that we will not (i) offer, pledge, announce the intention to sell, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase or otherwise transfer or dispose of, directly or indirectly, any shares of our common stock or securities convertible into or exercisable or exchangeable for any shares of our common stock or (ii) enter into any swap or other agreement that transfers, in whole or in part, any of the economic consequences associated with the ownership of any shares of our common stock or any such other securities, whether any of the transactions described in clause (i) or (ii) are to be settled by the delivery of shares of common stock or such other securities, in cash or otherwise, without the prior written consent of J.P. Morgan Securities Inc., Barclays Capital Inc., Credit Suisse Securities (USA) LLC and Deutsche Bank Securities Inc. for a period of 90 days after the date of this prospectus supplement, other than (i) the shares of our common stock to be sold hereunder, (ii) any shares of our common stock, options, or other securities issued under our existing management incentive plans, (iii) shares of our common stock, restricted stock, stock options or performance share units issued, or option grants resulting from reload rights associated with previously-awarded options, or other stock performance awards under our benefit and compensation plans, subject to certain exceptions, (iv) shares of our common stock (or securities convertible into or exchangeable for shares of our common stock) issued in an aggregate amount not to exceed, on a fully diluted basis, 5% of our outstanding common stock after giving effect to the issuance or sale of the common stock offered hereunder, in each case, in connection with the bona fide acquisition of technology, businesses, assets or property rights or the bona fide establishment of a strategic partnership or collaboration (including a joint venture) complementary to our business, (v) shares of our common stock issued in connection with the Marcellus Shale Transaction and (vi) shares of our common stock offered and sold in accordance with our 2009 Dividend Reinvestment and Stock Purchase Plan.

Certain of our directors and executive officers have entered into lock-up agreements with the underwriters prior to the commencement of this offering pursuant to which each of these

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persons or entities, with limited exceptions, will not, during the period ending 90 days after the date of this prospectus supplement, without the prior written consent of J.P. Morgan Securities Inc., Barclays Capital Inc., Credit Suisse Securities (USA) LLC and Deutsche Bank Securities Inc., (i) offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, or otherwise transfer or dispose of, directly or indirectly, any shares of our common stock or any securities convertible into or exercisable or exchangeable for our common stock (including, without limitation, common stock or such other securities which may be deemed to be beneficially owned by such directors and executive officers in accordance with the rules and regulations of the SEC and securities which may be issued upon exercise of a stock option or warrant), or publicly disclose the intention to make any offer, sale, pledge or disposition or (ii) enter into any swap or other agreement that transfers, in whole or in part, any of the economic consequences of ownership of our common stock or such other securities, whether any such transaction described in clause (i) or (ii) above is to be settled by delivery of our common stock or such other securities, in cash or otherwise, or (iii) make any demand for or exercise any right with respect to the registration of any shares of our common stock or any security convertible into or exercisable or exchangeable for our common stock. These restrictions do not apply to the transfer of (A) shares of our common stock acquired in open market transactions after the completion of this offering, (B) shares of our common stock sold for the cashless exercise of options to purchase our common stock for any withholding taxes on the exercise thereof or to pay the exercise price thereof pursuant to our existing employee benefit plans, (C) shares of our common stock pursuant to a pledge in effect on the date hereof as security for a margin account pursuant to the terms of such account and (D) any or all shares of our common stock or other securities if the transfer is other than a disposition for value and is by (x) gift, will or intestacy, (y) to a trust for direct or indirect benefit of the director/officer or an immediate family member of such person or (z) distribution to partners, members or shareholders of such director or executive officer; provided that, in the case of any gift, disposition, transfer or distribution pursuant to clause (D), each transferee shall execute and deliver to J.P. Morgan Securities Inc., Barclays Capital Inc., Credit Suisse Securities (USA) LLC and Deutsche Bank Securities Inc. a lock-up letter in the form of this paragraph.

We have agreed to indemnify the underwriters against certain liabilities, including liabilities under the Securities Act.

In connection with this offering, the underwriters may engage in stabilizing transactions, which involves making bids for, purchasing and selling shares of common stock in the open market for the purpose of preventing or retarding a decline in the market price of the common stock while this offering is in progress. These stabilizing transactions may include making short sales of the common stock, which involves the sale by the underwriters of a greater number of shares of common stock than they are required to purchase in this offering, and purchasing shares of common stock on the open market to cover positions created by short sales. Short sales may be "covered" shorts, which are short positions in an amount not greater than the underwriters' option to purchase additional shares referred to above, or may be "naked" shorts, which are short positions in excess of that amount. The underwriters may close out any covered short position either by exercising their option to purchase additional shares, in whole or in part, or by purchasing shares in the open market. In making this determination, the underwriters will consider, among other things, the price of shares available for purchase in the open market compared to the price at which the underwriters may purchase shares through

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the option to purchase additional shares. A naked short position is more likely to be created if the underwriters are concerned that there may be downward pressure on the price of the common stock in the open market that could adversely affect investors who purchase in this offering. To the extent that the underwriters create a naked short position, they will purchase shares in the open market to cover the position.

The underwriters have advised us that, pursuant to Regulation M of the Securities Act of 1933, they may also engage in other activities that stabilize, maintain or otherwise affect the price of the common stock, including the imposition of penalty bids. This means that if the representatives of the underwriters purchase common stock in the open market in stabilizing transactions or to cover short sales, the representatives can require the underwriters that sold those shares as part of this offering to repay the underwriting discount received by them. The underwriters may carry out these transactions on the New York Stock Exchange, in the over-the-counter market or otherwise.

These activities may have the effect of raising or maintaining the market price of the common stock or preventing or retarding a decline in the market price of the common stock, and, as a result, the price of the common stock may be higher than the price that otherwise might exist in the open market. If the underwriters commence these activities, they may discontinue them at any time. The underwriters may carry out these transactions on the New York Stock Exchange, in the over-the-counter market or otherwise.

Other than in the United States, no action has been taken by us or the underwriters that would permit a public offering of the securities offered by this prospectus supplement in any jurisdiction where action for that purpose is required. The securities offered by this prospectus supplement may not be offered or sold, directly or indirectly, nor may this prospectus supplement or any other offering material or advertisements in connection with the offer and sale of any such securities be distributed or published in any jurisdiction, except under circumstances that will result in compliance with the applicable rules and regulations of that jurisdiction. Persons into whose possession this prospectus supplement comes are advised to inform themselves about and to observe any restrictions relating to the offering and the distribution of this prospectus supplement. This prospectus supplement does not constitute an offer to sell or a solicitation of an offer to buy any securities offered by this prospectus supplement in any jurisdiction in which such an offer or a solicitation is unlawful.

This document is only being distributed to and is only directed at (i) persons who are outside the United Kingdom or (ii) to investment professionals falling within Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005 (the "Order") or (iii) high net worth entities, and other persons to whom it may lawfully be communicated, falling with Article 49(2)(a) to (d) of the Order (all such persons together being referred to as "relevant persons"). The securities are only available to, and any invitation, offer or agreement to subscribe, purchase or otherwise acquire such securities will be engaged in only with, relevant persons. Any person who is not a relevant person should not act or rely on this document or any of its contents.

In relation to each Member State of the European Economic Area which has implemented the Prospectus Directive (each, a "Relevant Member State"), from and including the date on which the European Union Prospectus Directive (the "EU Prospectus Directive") is implemented in that Relevant Member State (the "Relevant Implementation Date") an offer of securities described

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in this prospectus supplement may not be made to the public in that Relevant Member State prior to the publication of a prospectus in relation to the shares which has been approved by the competent authority in that Relevant Member State or, where appropriate, approved in another Relevant Member State and notified to the competent authority in that Relevant Member State, all in accordance with the EU Prospectus Directive, except that it may, with effect from and including the Relevant Implementation Date, make an offer of shares to the public in that Relevant Member State at any time:

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to legal entities which are authorized or regulated to operate in the financial markets or, if not so authorized or regulated, whose corporate purpose is solely to invest in securities;

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to any legal entity which has two or more of (1) an average of at least 250 employees during the last financial year; (2) a total balance sheet of more than €43,000,000 and (3) an annual net turnover of more than €50,000,000, as shown in its last annual or consolidated accounts;

•

to fewer than 100 natural or legal persons (other than qualified investors as defined in the EU Prospectus Directive) subject to obtaining the prior consent of the book-running manger for any such offer; or

•

in any other circumstances which do not require the publication by the Issuer of a prospectus pursuant to Article 3 of the Prospectus Directive.

For the purposes of this provision, the expression an "offer of securities to the public" in relation to any securities 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 securities to be offered so as to enable an investor to decide to purchase or subscribe for the securities, as the same may be varied in that Member State by any measure implementing the EU Prospectus Directive in that Member State and the expression EU Prospectus Directive means Directive 2003/71/EC and includes any relevant implementing measure in each Relevant Member State.

Certain of the underwriters and their affiliates have provided in the past to us and our affiliates and may provide from time to time in the future certain commercial banking, financial advisory, investment banking and other services for us and such affiliates in the ordinary course of their business, for which they have received and may continue to receive customary fees and commissions. In addition, from time to time, certain of the underwriters and their affiliates may effect transactions for their own account or the account of customers, and hold on behalf of themselves or their customers, long or short positions in our debt or equity securities or loans, and may do so in the future.

Lazard Frères & Co. LLC referred this transaction to Lazard Capital Markets LLC and will receive a referral fee from Lazard Capital Markets LLC in connection therewith.

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Legal matters

The validity of our common stock offered in this offering and certain other legal matters will be passed upon for us by Buchanan Ingersoll & Rooney, PC, Pittsburgh, Pennsylvania and Skadden, Arps, Slate, Meagher & Flom LLP, New York, New York. Certain legal matters will be passed upon for the underwriters by Simpson Thacher & Bartlett LLP, New York, New York.

Experts

The consolidated financial statements of EQT Corporation appearing in our Annual Report on Form 10-K for the fiscal year ended December 31, 2009 (including the schedule appearing therein) and the effectiveness of our internal control over financial reporting as of December 31, 2009 have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their reports thereon, included therein, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such reports given on the authority of such firm as experts in accounting and auditing.

The information included or incorporated by reference in this prospectus supplement as of December 31, 2009 relating to our estimated quantities of our proved natural gas and oil reserves is derived from an audit report prepared by Ryder Scott Company, L.P., independent petroleum engineers, as stated in its audit report with respect thereto. This information is included or incorporated in this prospectus supplement in reliance upon the authority of such firm as experts with respect to the matters covered by their report and the giving of their report.

S-27

12,500,000 shares

EQT Corporation

Common stock

Prospectus supplement

Joint Book-Running Managers

Senior Co-Managers

Co-Managers

March 10, 2010