DETROIT (AP)—Less than a week after reporting a sharp drop in September sales, GM said its U. S. sales chief is leaving as the automaker struggles to prop up its falling share of the market.

General Motors Co. CEO Fritz Henderson announced the departure of Mark LaNeve on Wednesday during a conference call with media and investors. LaNeve, 50, is taking a job at a firm outside the auto industry effective Oct. 15,GM spokesman John McDonald said.

LaNeve’s replacement has yet to be determined.

“We would benefit from fresh perspectives,” Henderson said.

GM’s September U. S. sales plunged 45 percent. So far this year, its sales are down 36 percent.