Pontiac-Buick-GMC Head to Leave

John Larson, 44, general manager of Pontiac-Buick-GMC since March 2005, is leaving General Motors Corp. after a 21-year career to join a company outside of the auto industry, the auto maker confirms.

GM says Larson will remain on the job at least through the end of next week.

Larson’s departure appears to have taken the auto maker by surprise. Last month, GM reorganized the Pontiac-Buick-GMC operations a bit, moving Steve Shannon, who had been overseeing the Buick brand under Larson, to Saab. Katherine Benoit was named executive director for Pontiac-Buick-GMC reporting to Larson.

No replacement has been named, and a spokesman says it is unclear when a decision will be made on Larson’s successor.

“I suspect people are working on that right now,” he says.