UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q/A

Amendment No. 1

For the quarterly period ended September 30, 2010, or

For the transition period from                          to                         .

Commission file number: 1-3754

ALLY FINANCIAL INC.

(Exact name of registrant as specified in its charter)

200 Renaissance Center

P.O. Box 200, Detroit, Michigan

48265-2000

(Address of principal executive offices)

(Zip Code)

(866) 710-4623

(Registrant’s telephone number, including area code)

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months, and (2) has been subject to such filing for the past 90 days.

Yes þ                    No ¨

Indicate by checkmark whether the registrant has submitted electronically and posted on its corporate Web site, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for a shorter period that the registrant was required to submit and post such files).

Yes þ                    No ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a nonaccelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer,” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).

Yes ¨                    No þ

At August 26, 2011 the number of shares outstanding of the Registrant’s common stock was 1,330,970 shares.

INDEX

2

3

EXPLANATORY NOTE

Ally Financial Inc. (Ally) is filing this amendment No. 1 (the Amendment) to its Form 10-Q for the three months ended September 30, 2010, which was originally filed with the U.S. Securities and Exchange Commission on November 9, 2010. The sole purpose of the Amendment is to file amended Exhibit 10.1. Certain portions of information that were omitted from Exhibit 10.1 that was originally filed with the Form 10-Q pursuant to a request for confidential treatment under Rule 24b-2 have now been included. The new Exhibit 10.1 is the only change being made to the Form 10-Q, and the information contained in this Amendment does not reflect events occurring subsequent to the filing of the Form 10-Q.

PART II — OTHER INFORMATION

Item 6. Exhibits

The exhibits listed on the accompanying Index of Exhibits are filed as a part of this report. This Index is incorporated herein by reference.

4

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 thereunto duly authorized, this 26th day of August 2011.

5

EXHIBIT INDEX

6