Labaton Sucharow, a top plaintiffs firm in the securities and antitrust class action world, has completed a leadership transition to install New York-based securities litigation partner Christopher Keller as the sole chairman after about a year of co-chairing the firm alongside name partner Lawrence Sucharow.

Sucharow stepped into a chairman emeritus role effective Jan 1. and will remain on the firm’s executive committee in a non-voting role. That change comes for Sucharow after more than 40 years at Labaton and more than 20 years in top leadership roles as managing partner and chairman or co-chair. The firm’s other namesake, Edward Labaton, remains a partner.