The Wall Street firm is once again top dog in the global M&A rankings, having advised on transactions worth close to $1.7 trillion this year, more than the annual economic output of Australia, including Friday’s $130 billion tie-up between U.S. chemical giants DuPont (DD.N) and Dow Chemical Co (DOW.N). Goldman’s No 1 status comes despite the bank having lost several veteran bankers this year, including Gordon Dyal, its former M&A chief and Jack Levy, one of four global co-chairmen of M&A, and reflects the enduring success of its partnership model, 15 years after the company went public.