A longtime trader for Bernard L. Madoff Securities LLC was sentenced Wednesday to 10 months of home confinement after his testimony helped convict five former coworkers for their roles in history’s largest Ponzi scheme.

David Kugel, 69, apologized before Southern District Judge Laura Taylor Swain. “The guilt, embarrassment and humiliation have become part of my DNA,” Kugel told her. “In my mind, I’ve gone from being an American success story to being an American tragedy.”