Investors yanked $4 billion from Renaissance Technologies’ largest hedge fund over the past several months, as the quantitative offering suffered—like fellow quants—from the market volatility set off by the subprime slide.

Following the outflows of the last four months, the Renaissance Institutional Equities Fund now manages between $21 billion and $22 billion. When Renaissance chief James Simons unveiled the fund in 2005, he boasted it had a capacity of $100 billion. But the fund, which fell by less than 1% last year, has failed to match the remarkable success of the East Setauket, N.Y., firm’s flagship: It has produced annualized returns of 9.7% since inception, more or less in line with the Standard & Poor’s 500. Last year, Renaissance limited inflows into the Institutional Equities fund to $1.5 billion per month.

In other firm news, SAC Capital finance chief James Rowen has joined the Long Island firm as chief operating officer, replacing Stephen Daffron. Dan Berkowitz, accounting and operations chief at SAC, takes Rowen’s place at the Stamford, Conn.-based hedge fund giant.