The US M&A market saw a 20% leap in 2003 in the latest sign of a market comeback for corporate

America, with New York leader Simpson Thacher & Bartlett emerging as the top-ranked legal adviser.

The Thomson Financial research shows returning confidence in the US M&A market, which saw a 19.6% value increase up to $525.6bn from 2002′s $439.5bn.

The largest US deal was Bank of America's $47bn acquisition of FleetBoston Financial in November, which came amid a series of multi-billion dollar transactions to hit the US in the closing months of 2003.

Simpson Thacher topped the US table with 71 announced deals worth $102.5bn, against an 11th place ranking in Thomson's 2002 tables.

The firm secured a number of key instructions in 2003 such as advising The St Paul on its $16.5bn merger with Travelers Property Casualty, Wellpoint Health Networks on its $16.4bn merger with Anthem and Manulife Financial on its $11bn merger with John Hancock Financial Services.

The firm's highly regarded leveraged buy-out practice also benefited from continued activity from private equity clients.

Simpson Thacher head of corporate Philip Ruegger told Legal Week Global: "We had a nice share of the M&A activity. Even though we were not involved in Bank of America/FleetBoston, we did very well with insurance clients."

The previous year's top-placed firm, Skadden Arps Slate Meagher & Flom, meanwhile, fell to fourth place, with Latham & Watkins and Cleary Gottlieb Steen & Hamilton taking second and third place respectively thanks to the FleetBoston deal.

Other major deals in the US last year included Oracle's $6.3bn hostile bid for PeopleSoft and Liberty Media Group's $7.9bn acquisition of QVC.

Ruegger added: "Generally, there is guarded optimism for 2004 as the corporate world seems to be returning to the M&A arena."