George Canellos will step down as co-head of the Enforcement Division at the U.S. Securities and Exchange Commission later this month, the agency announced today.

Canellos and Andrew Ceresney made history last year when the two were named co-heads of the division, which until then had always had a single leader. With Canellos’ departure, Ceresney will become the sole head of the 1,300-person division.