John Mack's reported efforts to lure a senior ex-colleague from Morgan Stanley to Credit Suisse First Boston would be the chief executive's latest attempt to impose a one-bank culture over the firm he inherited last summer from Allen Wheat.

Mack is to poach Walid Chammah from the firm he left last year, to co-head investment banking with Adebayo Ogunlesi, head of CSFB's energy investment banking group, the New York Times reported Tuesday. The new role would be a big step-up for Chammah, who currently heads debt capital markets at Morgan Stanley.