On May 1, A&O Shearman goes live: an unprecedented combination of two elite Big Law firms with roots in either side of the Atlantic that would create a $3.5 billion integrated law firm ranking behind only the industry titans of Kirkland & Ellis and Latham & Watkins.

When news that U.K-founded Allen & Overy was to merge with U.S.-founded Shearman & Sterling broke in May 2023, it caused as much shock as feelings of inevitability.