Ken Griffin’s Citadel LLC lost three senior executives at the securities unit, bringing to nine the number of top-level employees who have departed in the last 15 months.

Chris Boas, head of credit markets for Citadel Securities, Brad Kurtzman, who ran equity derivatives sales and trading, and Carl Mayer, head of leveraged finance, all left, the company confirmed.

The exodus of senior talent started when Rohit D’Souza, who Griffin had hired to build the newly-formed securities unit, left after one year.