Karen Seward, the former global litigation head and U.S. co-chair of Allen & Overy, is to retire from the A&O Shearman partnership at the end of this year, according to people with knowledge of the firm.

Seward, who was seen as a potential successor to Wim Dejonghe as head of A&O Shearman following the completion of the firm’s merger, will step down as a partner on December 31 this year. A&O Shearman said that she would continue to work with the firm as a consultant.