Ken Brody, a co-founder of $8.2 billion hedge fund Taconic Capital Advisors, is retiring from the firm as of January 1, according to an investor letter sent on Tuesday.

Brody, age 70, founded the firm with Frank Brosens, age 56, in 1999. Brosens will be staying on to head the New York-based multi-strategy, event-driven fund. Brody said in the letter that the pair planned the transition "over a considerable period of time".