Jay Wintrob will take over as chief executive of downtown Los Angeles investment management firm Oaktree Capital Group next month, the firm announced Monday.

Wintrob, who ran the American International Group’s life and retirement division until leaving last month, will be the first chief executive of the investment company, which was founded by billionaires Bruce Karsh and Howard Marks.

Karsh had been the firm’s top executive, with the titles of president and chief investment officer. He and Marks, now the firm’s chairman, will share the title of co-chairman.

Wintrob has been on Oaktree’s board since 2011. He starts his role as chief executive on Nov. 1.