A managing director and chief operating officer for global equities at Ken Griffin's $15 billion Chicago-based hedge fund firm Citadel, is stepping down, according to two people familiar with the situation.

Jonathan Ledden, a member of the management committee of Citadel Global Equities, is retiring after almost a decade at the firm, one of the people said. Chicago-based Ledden will remain in the office until the end of August and help to appoint his successor, the person said.