Simpson Thacher & Bartlett’s banking and credit practice, one of the firm’s most prominent groups, is shifting its leadership, with partners Alexandra Kaplan and Brian Steinhardt taking over as co-heads of the practice, the firm said Tuesday.

Patrick Ryan, who was leading the group since 2009, is stepping down. He will continue to practice within the group, sources familiar with the change said. It’s a significant practice area change for Simpson, since the firm’s banking and credit group is Band One under Chambers, and Ryan has led the group for about 15 years.