Welch has only headed the unit since early last year, but had been involved in the Swiss bank’s arm since 1997.
And of those 16 years at the institution, eight were spent heading the energy unit in the investment bank. He has left to work for client Energy Transfer Partners.
Drew joined the bank in 2003 and currently co-heads global market solutions. Stevenson joined in 1989 and runs the financial institutions arm.
They will both stay in those roles, splitting the top job at the investment bank between them.
Credit Suisse has been repositioning itself in the past year, cutting back on the capital intensive investment banking operations and cutting 2,300 staff in the process.