Bank of America took the title of largest U.S. bank, by assets, after it completed its purchase of embattled Wall Street securities trading firm Merrill Lynch this week. The Charlotte, N.C.-based Bank of America now controls $2.7 trillion.

Wells Fargo and PNC Financial Services Group also finalized acquisitions of rival banks this week in the midst of an economic crisis that is redefining banking in the United States.

Each of the three large banks is expected to lay off employees as they roll the aquired companies into their own organizations.