Musical Chairs: Alan Cohen, Sarah Smith, Brian Lee.

Alan Cohen, Goldman Sachs head of compliance and the longest-serving internal cop on Wall Street, is vacating his seat after 13 years. He will become a senior adviser to the firm’s executive office, and will be replaced by the chief accounting officer, Sarah Smith.

Prior to joining Goldman, Mr. Cohen spent 15 years as a partner at law firm O’Melveny & Myers where he ran the white-collar crime and regulatory practice group. Before that, he was a federal prosecutor in New York and eventually headed a task force aimed at rooting out fraud in securities and commodities trading.

Mr. Cohen joined Goldman as partner in 2004, a rare instance of a person entering the firm at that level rather than having to work his way up the ranks. He has outlasted compliance chiefs at all other big bank rivals. In recent weeks, he has sold about 10,000 shares of Goldman stock worth about $2 million - the cost to exercise options means he pocketed far less.

Sarah Smith has been …   Goldman’s chief accounting officer since 2002, and joined the firm-wide management committee in an expansion of that body in 2014. She is among the most senior women at a firm with relatively few at the top levels. Ms. Smith, in turn, will be replaced by her deputy, Brian Lee.