UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 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): September 14, 2012

AMERICAN INTERNATIONAL GROUP, INC.

(Exact name of registrant as specified in its charter)

180 Maiden Lane

New York, New York 10038

(Address of principal executive offices)

Registrant’s telephone number, including area code: (212) 770-7000

(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 8 — Other Events

Item 8.01. Other Events.

On September 14, 2012, the United States Department of the Treasury (“Treasury”), as the selling shareholder, closed the sale of 636,923,075 shares of common stock, par value $2.50 per share (“AIG Common Stock”), of American International Group, Inc. (“AIG”), at an initial public offering price of $32.50 per share (the “Offering”). This number of shares sold in the Offering included 83,076,922 shares sold pursuant to the exercise in full of the underwriters’ option to purchase additional shares of AIG Common Stock to cover over-allotments. AIG purchased 153,846,153 shares of AIG Common Stock in the Offering at the initial public offering price for an aggregate purchase amount of approximately $5.0 billion.

In connection with the Offering, AIG entered into an Underwriting Agreement, dated September 10, 2012 (the “Underwriting Agreement”), among AIG, Treasury and Citigroup Global Markets Inc., Deutsche Bank Securities Inc., Goldman, Sachs & Co. and J.P. Morgan Securities LLC, as representatives of the several underwriters named therein. The Underwriting Agreement is filed as Exhibit 1.1 to this Current Report on Form 8-K. The exhibits are incorporated by reference into the Registration Statement (No. 333-182469) related to the Offering.

Section 9 — Financial Statements and Exhibits

Item 9.01 Financial Statements and Exhibits.

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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.

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