[ by Melanie Gretchen ] Another Goldman Sachs partner is stepping down, the investment bank said in an internal memo on Tuesday.  Following his retirement, one of Goldman Sachs’s co-heads of global mergers and acquisitions, Yoël Zaoui, will become a senior director, continuing to contribute his advice and counsel. A Goldman Trend. The latest loss among the ranks of Goldman's executives and its partnership, Mr. Zaoui, 51, follows the departure of George N. Mattson, a senior industrials banker; Luca Ferrari, the head of mergers and acquisitions in Northern Europe; and Edward K. Eisler and David B. Heller, who were the leaders of the firm’s securities business.  Upon Mr. Zaoui's retirement, his co-head, Gene Sykes, will assume sole oversight of the global mergers group. Mr. Zaoui was born in Morocco and educated in France and the United States before joining Goldman in 1988.  During his 24 years at the firm, he became managing director in 1997 and partner in 1998, after which he began assuming management positions, including overseeing European mergers and then investment banking for the Continent.  In 1996, he won the John L. Weinberg Award for outstanding performance in support of the firm’s Business Principles and service to our clients. For further details, go to [Dealbook, 4/10/12].