(Bloomberg) -- Renaissance Technologies tapped longtime employee David Lippe to be co-chief executive officer of the $40 billion hedge fund firm, according to a note sent to investors. 

Lippe will start his new job alongside CEO Peter Brown on July 1. Brown has been running the firm on his own since 2018, when his former co-head, Robert Mercer, stepped down.  

“The two of us have worked closely together since David joined Renaissance in 2001,” Brown wrote Thursday in the note. “Renaissance’s bench of outstanding scientists and other professionals is deeper than it ever has been and positions the company well.”

Lippe’s lieutenant, James Mammen, will replace him as head of institutional funds. 

The firm’s stock fund, known as RIEF, climbed 8.6% this year through November. 

Renaissance also runs the highly profitable Medallion Fund, which is open only to employees. 

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