Sullivan & Cromwell and Skadden, Arps, Slate, Meagher & Flom have emerged as the top U.S. law firms in European M&A over the last three years, according to research produced for Legal Week that shows the pair have worked on the highest value of deals over the period.

Sullivan ranked first in the value tables for U.K. and Europe, according to figures compiled by Legal Week‘s data partner Mergermarket. The New York firm has advised on 173 European deals worth a total value of �839.7 billion ($1.2 trillion) since November 2004 and 60 deals worth a total of �244 billion ($357.5 billion) in the U.K.