UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): August 6, 2010

Mirant Corporation

(Exact Name of Registrant as Specified in Charter)

Registrant’s telephone number, including area code: (678) 579-5000

N/A

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

Section 2 – Financial Information

On August 6, 2010, Mirant Corporation (the “Company,” “Mirant,” “we,” “us,” or “our”) issued a press release announcing its financial results for the quarter ended June 30, 2010. A copy of Mirant’s August 6, 2010, press release is furnished hereto as Exhibit 99.1 and incorporated by reference herein. The press release contains certain forward-looking statements, all of which are subject to the cautionary statement about forward-looking statements set forth therein. Except as otherwise provided in the press release, the press release speaks only as of the date of such press release and it shall not create any implication that the affairs of Mirant will have continued unchanged since such date.

We use certain non-GAAP financial measures in the press release and on our earnings conference calls. These non-GAAP financial measures include adjusted net income, adjusted EBITDA, realized and unrealized gross margins, adjusted gross margin, adjusted operations and maintenance expenses, adjusted net cash provided by (used in) operating activities, adjusted free cash flow and adjusted free cash flow (without MD HAA and Marsh Landing). The definitions of these non-GAAP financial measures, together with a discussion of the usefulness and purpose of such measures, is provided in the explanations attached hereto as Exhibit 99.2. Reconciliations of each of these non-GAAP measures to the most directly comparable GAAP measure can be found either in our earnings press release or in the investor presentation that we intend to utilize on our earnings conference call, which will be posted on our website prior to the commencement of the conference call.

The information contained in Item 2.02 in this Current Report on Form 8-K is to be considered “furnished” pursuant to Item 2.02 of Form 8-K and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or otherwise subject to the liabilities of that Section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended, nor shall it be deemed incorporated by reference in any Mirant filing or report with the Securities and Exchange Commission, whether made before or after the date hereof, except as shall be expressly set forth by specific reference in such a filing or report.

Section 9 – Financial Statements and Exhibits

(d) Exhibits.

Additional Information and Where To Find It

This report does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval nor shall there be any sale of securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. In connection with the proposed merger between Mirant and RRI Energy, on May 28, 2010, RRI Energy filed with the SEC a registration statement on Form S-4 that includes a preliminary joint proxy statement of RRI Energy and Mirant and that also constitutes a preliminary prospectus of RRI Energy. On July 6, 2010, RRI Energy amended these materials. These materials are not yet final and will be further amended. Mirant and RRI Energy will distribute the final joint proxy statement/prospectus to their respective shareholders. Mirant and RRI Energy urge investors and shareholders to read the registration statement, and any other relevant documents filed with the SEC, including the preliminary joint proxy statement/prospectus that is a part of the registration statement, and the definitive joint proxy statement/prospectus, when available, because they contain or will contain important information. You may obtain copies of all documents filed with the SEC regarding this transaction, free of charge, at the SEC’s website (www.sec.gov). You may also obtain these documents, free of charge, from Mirant’s website (www.mirant.com) under the tab “Investor Relations” and then under the heading “SEC Filings,” and from RRI Energy’s website (www.rrienergy.com) under the tab “Investor Relations” and then under the heading “Company Filings.”

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Participants in the Merger Solicitation

Mirant, RRI Energy, and their respective directors, executive officers and certain other members of management and employees may be soliciting proxies from Mirant and RRI Energy shareholders in favor of the merger and related matters. Information regarding the persons who may, under the rules of the SEC, be deemed participants in the solicitation of Mirant and RRI Energy shareholders in connection with the proposed merger is contained in the preliminary joint proxy statement/prospectus and will be contained in the definitive joint proxy statement/prospectus when it becomes available. You can find information about Mirant’s executive officers and directors in its definitive proxy statement filed with the SEC on March 26, 2010 and supplemented on April 28, 2010. You can find information about RRI Energy’s executive officers and directors in its definitive proxy statement filed with the SEC on April 1, 2010. Additional information about Mirant’s and RRI Energy’s executive officers and directors can be found in the above-referenced Registration Statement on Form S-4. You can obtain free copies of these documents from Mirant and RRI Energy as described above.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date: August 6, 2010

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