Two Sigma cofounders David Siegel and John Overdeck stepped back as co-CEOs of the firm in September.Two SigmaTwo Sigma laid off 200 employees Thursday, 10% of the $60 billion firm's workforce.The hedge fund is run by co-CEOs Carter Lyons and Scott Hoffman, who took over for Two Sigma's billionaire cofounders in September.The firm is planning to continue to invest in its core strategies, a person close to the manager said.Thursday brought the latest twist in a year full of them for $60 billion Two Sigma.The New York-based quant giant has cut 200 jobs — roughly 10% of its overall workforce.