Simpson Thacher & Bartlett has outpaced strong runs from rival firms Shearman & Sterling, Weil Gotshal & Manges and Cleary Gottlieb Steen & Hamilton to take the top spot in 2005′s highly active US M&A market, according to new research.

Thomson Financial’s 2005 deal rankings show Simpson Thacher knocking Skadden Arps Slate Meagher & Flom from the top spot for announced US M&A deals after advising on 134 ranked deals with a value of $333.8bn (£193.1bn).