The former co-head of Citigroup’s prime brokerage has joined Fidelity Investments to run the mutual fund giant’s business in the space.

Thomas Tesauro was ousted at Citi, along with his co-chief Ali Hackett, amidst a major shakeup of the troubled bank’s hedge fund services group. But he’s back in a similar role at Boston-based Fidelity, which hopes to boost its stock-lending and clearing services for hedge funds in an effort to make up for lower fees from its main money management business.

“Driven by unprecedented market volatility, and uncertainty surrounding many of the street’s traditional prime brokers, a growing number of hedge funds are shifting assets to strong, reputable firms like Fidelity,” Tesauro’s new boss, Fidelity Capital Markets President Mark Haggerty, said in a statement.

Tesauro jumps to Fido from S3, a New York-based risk management firm, which he joined in December.