Credit Suisse First Boston has fired about 15% of its investment bankers today. Bloomberg news service says that an internal memo indicates that 300 investment bankers are being let go as a cost-cutting measure.

The cuts include at least 50 managing directors. “These reductions will cover all levels of professional staff, every product and industry group and all regions around the globe,” says head of investment banking, Adebayo Ogunlesi, in the memo. “These were very difficult decisions, but they were decisions that could not be avoided if we are to position CSFB for future growth and profitability.”

New CEO John Mack, known on the street as “Mack the Knife” was brought in to get the firm’s spending under control last July. He has already cut 9% of CSFB’s total staff in earlier cost cutting moves. “For now, these reductions position us well to compete in the economic environment,” CSFB spokeswoman Jeanmarie McFadden told Bloomberg. “But we will continue to evaluate needs and adjust headcount accordingly.”