As iconic brands are snapped up and corporations merged and swallowed in a record-breaking whirl of deals, there has been one constant: Goldman Sachs Group Inc (GS.N), Reuters reports.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.Becoming a partner at Goldman Sachs is still one of the most coveted promotions on Wall Street, and those who make the cut represent a powerful network of well-connected dealmakers.The partnership, along with the bank`s commitment to remaining a full-service investment bank despite post-crisis rules that make it more difficult to trade, have given it an edge over rivals such as Morgan Stanley (MS.N), which has a strong emphasis on wealth management.‘Goldman is still run as a partnership, and delivers the entire firm,’ said Brad Hintz, a former Lehman Brothers Holdings Inc chief financial officer and financial analyst who is now a business professor at the NYU Stern School of Business.The 146-year-old investment bank has ranked No. 1 in the global M&A league tables every year since 1997, with the exception of 2009 and 2010, when it ranked No. 2 behind Morgan Stanley, according to Thomson Reuters data. This year, the bank advised on all the mega deals in pharmaceuticals, energy, beverages and now chemicals, where it is set to split $80 million to $100 million in DuPont advisory fees with Evercare Partners Inc (EVR.N).Trailing Goldman Sachs in the global M&A league tables this year are Morgan Stanley, JPMorgan Chase & Co (JPM.N), Bank of America Corp (BAC.N) and Citigroup Inc (C.N).