Fifth Third Bank (5/3 Bank) is a U.S. regional banking corporation, headquartered in Cincinnati, Ohio at Fifth Third Center, and is the principal subsidiary of holding company Fifth Third Bancorp. The company operates under an Ohio charter. Its main businesses include branch banking, commercial banking, consumer lending, payment processing, investment advising, and title insurance.

Fifth Third Bank's corporate history began on June 17, 1858, when the Bank of the Ohio Valley opened in Cincinnati. Five years later, the Third National Bank organized on June 23, 1863. On April 29, 1871, the younger bank acquired the older one, beginning a long history of acquisitions and mergers that absorbed and renamed numerous smaller banks.

Fifth Third's unusual name is the result of the June 1, 1908, merger of Third National Bank and Fifth National Bank, to become the Fifth-Third National Bank of Cincinnati (the hyphen was later dropped). While Third National was the senior partner, the merger took place when prohibitionist ideas were gaining popularity, and it is legend that "Fifth Third" was better than "Third Fifth," which could have been construed as a reference to three fifths of alcohol. The name went through several changes over the years until March 24, 1969, when it was changed to Fifth Third Bank.

In 1999, the company completed the acquisition of Enterprise Federal Bancorp Inc., one of the biggest thrifts in the Cincinnati area. The purchase, estimated at $96.4 million, added 11 branches to Fifth Third in greater Cincinnati. Fifth Third also acquired Ashland Bankshares, Inc. and its subsidiary Bank of Ashland, both based in Kentucky. The $80-million purchase gave Fifth Third four more branches and $160 million in assets. Fifth Third also began to implement plans to expand further into Florida and acquired South Florida Bank Holding Corp. in June, adding another four branches to its Florida roster. Additional expansion into the Cleveland area came with the $204-million acquisition of Emerald Financial Corp. Fifth Third also acquired Cleveland-based Emerald Financial Corp. and its subsidiary, Strongsville Savings Bank.

In November 2000, Fifth Third announced the purchase of Old Kent Bank of Western Michigan. This added more than 300 full-service banking centers in Indiana, Illinois and Michigan.

In May 2007, Fifth Third announced the acquisition of R-G Crown Bank of Casselberry, Florida, a transaction that closed in the fourth quarter of 2007 and which added 30 branches in Florida and three in Georgia.

On August 16, 2007, Fifth Third announced the purchase of First Charter Bank of Charlotte, North Carolina. As part of this transaction, Fifth Third entered the North Carolina market with 57 branches, and the Atlanta market with two branches. The Federal Reserve Board approved the transaction for Fifth Third Bank to acquire First Charter, April 16, 2008. The acquisition completed in June 2008.

On September 25, 2007, Fifth Third announced the acquisition of nine branch locations in Atlanta, GA, from First Horizon National Corporation. First Horizon canceled the sale February 7, 2008, as the sale price suddenly became unacceptable to FHN. Then, news outlets reported that the sale was reinstated March 25, 2008.

On October 31, 2008, the Federal Deposit Insurance Corporation (FDIC) announced that all deposits of Florida-based Freedom Bank, which ceased operation that day, would be assumed by Fifth Third Bank.

On March 30, 2009, Fifth Third announced a joint venture with Advent International, in which Advent would purchase 51% of its credit card processing business, Fifth Third Processing Solutions. The new company Fifth Third Processing Solutions LLC began operation June 2009.

Fifth Third was rumored to be one of the front runners alongside Huntington Bancshares to buy the National City branches in the Pittsburgh and Erie regions that the United States Department of Justice required PNC Financial Services to sell as part of PNC's 2008 acquisition of National City. Had Fifth Third bought the branches, it would have greatly expanded the bank's presence in the Pittsburgh region where Fifth Third has opened a small handful of branches over the past few years as opposed to acquiring a rival bank, as well as enter the Erie market. Ultimately, PNC sold the bulk of the overlapping branches to First Niagara Bank. In 2015, Fifth Third announced it would exit the Pittsburgh market by selling its retail branches to locally based FNB Corporation, but it would continue to do commercial banking in Pittsburgh.

On October 28, 2014, Fifth Third announced plans to move its Michigan regional headquarters from Southfield to downtown Detroit in what will be named the Fifth Third Bank Building at One Woodward. The bank will occupy about 62,000 sq ft (5,800 m) of the structure and has also pledged to invest $85 million in the city of Detroit. The office had 150 employees.

In January 2007, The New York Times published an article entitled Data Breach Could Affect Millions stating "Yesterday, Fifth Third Bank of Cincinnati was identified as the sponsoring bank that handles TJX’s accounts, which makes it responsible for ensuring that the retailer met the industry’s data security standards." It was later found that potentially 45.7 million credit card numbers were compromised. This, from the Associated Press, "TJX says its computer systems were first breached in July 2005 by a hacker or hackers who accessed information from customer transactions dating to January 2003. TJX says it didn’t learn of the breach until about three months ago.... The filing also says, “We believe that the intruder had access to the decryption tool for the encryption software utilized by TJX.”

In August 2014, the Department of Justice filed a settlement with Fifth Third Mortgage Company resolving allegations that the bank engaged in a pattern of discrimination on the basis of disability and receipt of public assistance in violation of Equal Credit Opportunity Act. Under the settlement, Fifth Third was required to establish a settlement fund of $1.5 million to compensate eligible mortgage loan applicants who were asked to provide a letter from their doctor to document the income they received from Social Security Disability Insurance.

Fifth Third owns the naming rights to:

Official website