In 1976, Tamraz moved into United States financial markets with his acquisition of Bank of the Commonwealth, a Michigan-based bank with 50 branches. He strengthened and expanded the bank until 1983, when it was merged into the founding of Comerica, Inc., now one of the largest super-regional U.S. bank holding companies. The merger made Tamraz the largest single shareholder in Comerica at the time, before selling out to finance the Tamoil acquisition described below. Comerica currently has assets of $64 billion and a market capitalization of $5.6 billion.