The top executive of Citadel Investment Group's investment banking unit has left the firm, a company spokeswoman confirmed on Saturday.

Todd Kaplan, who joined the Chicago-based hedge fund firm in March as it launched its new investment banking business, resigned from the company on Friday, Citadel spokeswoman Katie Spring said.

Kaplan, a high-profile hire, had spent more than 20 years at Merrill Lynch before joining Citadel.

People from the investment banking unit who had reported to Kaplan will now report to Patrik Edsparr, global chief executive of Citadel Securities, the Wall Street Journal said.

(Reporting by Brad Dorfman, Editing by Sandra Maler)