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 22, 2011

SunTrust Banks, Inc.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code (404) 588-7711

Not Applicable

(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):

On September 22, 2011, SunTrust Banks, Inc. determined that it may participate by bidding in the ongoing auctions of warrants to purchase its common stock. Therefore, the information included herein supplements the Preliminary Prospectuses (the “Prospectuses”), dated September 21, 2011, included in the Registration Statement on Form S-3 (File No. 333-161712). Unless otherwise mentioned or unless the context requires otherwise, all references herein to “SunTrust,” “we,” “us,” “our” or similar references mean SunTrust Banks, Inc. and its subsidiaries.

The following information supplements the information in the Prospectuses under the heading “Summary—Summary of the Offering.”

The following information supplements the information in the Prospectuses under the heading “Risk Factors—Risks Related to the Auction Process.”

We are permitted to participate in the auction process and, if we do so, that could have the effect of raising the clearing price and decreasing liquidity in the market for the warrants.

We are permitted (but we are not required) to submit bids in the auction process. You will not be notified by either the auction agent, the network brokers or the selling security holder whether we have bid in the auction process or, should we elect to participate in the auction process, the terms of any bid or bids we may place. Although we will not receive preferential treatment of any kind and would participate on the same basis as all other bidders, except that we are required to submit any final bid we may enter by 6:00 p.m., New York City time, on the day on which the auction process is conducted, in some cases the submission of bids by us could cause the clearing price in the auction process to be higher than it would otherwise have been (although in such a case we would still be required to purchase any warrants for which we had submitted bids at the clearing price). In addition, to the extent we purchase any warrants, the liquidity of any market for the warrants may decrease, particularly if any such purchases represent a significant percentage of the outstanding warrants.

The following information supplements the information in the Prospectuses under the heading “Auction Process—Eligibility and Account Status.”

We will be allowed to bid in the auction process and, if we do participate, we will not receive preferential treatment of any kind and would participate on the same basis as all other bidders, except that we are required to submit any final bid we may enter by 6:00 p.m., New York City time, on the day on which the auction process is conducted.

The following information supplements the information in the Prospectuses under the heading “Auction Process—The Auction Process—The bidding process.”

We will be allowed (but we are not required) to bid in the auction process. If we decide to bid, we will not receive preferential treatment of any kind and would participate on the same basis as all other bidders, except that we are required to submit any final bid we may enter by 6:00 p.m., New York City time, on the day on which the auction process is conducted. You will not be notified by either the auction

agent, the network brokers or the selling security holder whether we have bid in the auction process or, should we elect to participate in the auction process, the terms of any bid or bids we may place. We will be required to submit any bids we make through the auction agent. The submission of issuer bids may cause the clearing price in the auction process to be higher than it would otherwise have been absent such bids.

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We have filed a registration statement (including a prospectus) with the Securities and Exchange Commission (the “SEC”) for the offerings to which this communication relates. Before you invest, you should read the prospectus in that registration statement and other documents we have filed with the SEC for more complete information about the issuer and these offerings. You may get these documents for free by visiting EDGAR on the SEC Web site at www.sec.gov. Alternatively, you may request a prospectus by contacting Deutsche Bank Securities Inc., Prospectus Department, Harborside Financial Center, 100 Plaza One, Jersey City, New Jersey 07311-3988, telephone: 1-800-503-4611, or by emailing prospectus.cpdg@db.com.

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.