New York duo Wachtell Lipton Rosen & Katz and Simpson Thacher & Bartlett have underlined a strong run in the surging US deal market with the pair securing the lead positions in the US M&A rankings for the first half of 2005.

Wachtell scooped top spot in the table after advising on 36 deals worth $156.9bn (£90bn), up by 6% on 2004′s half-year total, with Simpson Thacher just behind with 59 deals worth $154.7bn (£88bn) according to research from Thomson Financial.