Christopher Willcox spent decades rising through the ranks at Wall Street firms before landing at Nomura Holdings during one of the most tumultuous periods in the Japanese brokerage’s history.

Now, just 17 months after he arrived at Nomura to help run its U.S. business, Willcox is tasked with turning around the firm’s global investment bank. He takes over as head of the firm's wholesale division on Saturday from Steve Ashley, 55, whose tenure was marked by overhauls, strategy changes and roughly $2 billion of losses tied to the implosion of Bill Hwang’s Archegos Capital Management.

Willcox, 54, a veteran of JPMorgan Chase & Co. and Citigroup, will inherit a business that’s changing tack after some of its most challenging years — which also saw it post losses on trades linked to U.K. inflation and face costly litigation in the United States. Nomura is trying to cut its reliance on income from volatile trading for more stable revenue streams such as advising clients on deals — which has doubled over the past two years — and wealth management.