Bank of America (BAC) shocked the market a bit last week, when it announced the departure of Bruce Thompson, the bank’s chief financial officer and chief risk officer, without a great deal of explanation as to why Thompson was leaving after more than five years.

Now, a Reuters report sheds some light onto the reason that Thompson is stepping down.

According to the Reuters report, citing sources, Thompson wanted to lead Bank of America, not just manage its finances, and worried that he’d have to wait too long to replace current CEO Brian Moynihan.

From the Reuters report:

Thompson's interest in heading a company was at least one reason for his leaving, the sources said: his ambitions ranged beyond managing cost cutting campaigns and fixing a big bank's books.

Thompson, 51, believed he would have a long wait to be CEO of Bank of America, given that CEO Brian Moynihan is just 55, one of the two sources said. The two sources said they spoke to Thompson.

A previous Reuters report speculated that Thompson’s departure may have been related to the results of March’s Dodd-Frank Stress Test.

From the earlier Reuters report:

Thompson was one of the senior executives who played an important role in the firm's stress-test submissions to the U.S. Federal Reserve.

However, BofA failed to win unconditional approval from the U.S. Federal Reserve in March and was asked to get a better grip on its internal controls and data models.