The transaction, which has been approved by the boards of both companies, is subject to approval by Wachovia's shareholders and regulators and must close by Dec. 31.
The Wachovia acquisition caps a wave of unprecedented upheaval in the financial sector in the past six months that has redefined the banking industry, starting with the government-led forced sale of Bear Stearns Cos. to JPMorgan in March.
The failure of IndyMac Bancorp in July reignited investors' fears about the stability of the financial sector, which led to the eventual takeover of struggling mortgage lenders Fannie Mae and Freddie Mac. Earlier this month, officials seized both Fannie and Freddie, temporarily putting them in a government conservatorship, replacing their chief executives and taking a financial stake in the mortgage finance companies.
After U.S. regulators made it clear that they would not bail out struggling investment bank Lehman Brothers Holdings Inc., rival Merrill Lynch & Co. arranged a hasty deal to be bought by Bank of America Corp. for $50 billion in stock.