Former chief executive officer of Merrill Lynch & Co. John Thain has resigned from Bank of America Corp, three weeks after the companies merged.

Thain's resignation came after a short meeting with Bank of America's CEO Ken Lewis Thursday, CNBC reported. Apparently Lewis lost confidence in Thain when he couldn't give a good explanation about the giant losses Merrill Lynch posted in its fourth quarter, the Wall Street Journal reported quoting a person familiar with the matter.

The relationship between Thain and Lewis became strained when last week, Merrill Lynch announced an unexpected loss of $15.31 billion, according to the source.

Bank of America, which closed the Merrill buyout on Jan 1, asked for a $20 billion bailout from the government last week to absorb Merrill's loss.

Thain had been positioned as head of global banking, securities and wealth management of Bank of America. He reportedly spent $1.22 million redesigning his office when he became CEO of Merril Lynch, CNBC noted.

Shares of Bank of America dropped 13.32 percent to $5.79 at 1:07 p.m. on the New York Stock Exchange Thursday.