Erin Callan, 42, did not last long in Wall Street’s executive suite. Her reign as CFO of Lehman Brothers was just shy of six months. She was ousted in June, becoming a high-profile victim of the subprime crisis. But market participants expect that the former investment banker will stay longer in her new role as global head of hedge funds at Credit Suisse, which she joins this month. In recent years the Swiss bank has been courting hedge fund managers, and it hopes Callan will boost those efforts. Although her departure from Lehman followed a clash with scrappy hedge fund manager David Einhorn, who claimed that the bank had not properly accounted for certain losses, Callan boasts a long, largely positive history in the hedge fund world dating back to her time as head of investment banking at Lehman, where she worked for 13 years. She was the lead banker on the IPOs of New York’s Fortress Investment and Och-Ziff Capital Management.