DETROIT  General Motors said Wednesday that it would shut down its Saturn division by next year after Roger Penske abruptly cut off talks to acquire the brand.

The Penske Automotive Group said it could not proceed with the deal because another auto manufacturer, which it did not identify, said it would not build vehicles to be distributed under the Saturn brand name.

The decision by Penske Automotive stunned G.M. and Saturn dealers, who had hailed Mr. Penske, who has built a track record of successful turnarounds, as the savior of the brand that G.M. was forced to sell as part of its government-financed bankruptcy reorganization.

“Today’s disappointing news comes at a time when we’d hoped for a successful launch of the Saturn brand into a new chapter,” G.M.’s chief executive, Fritz Henderson, said in a statement. “We will be working closely with our dealers to ensure Saturn customers are cared for as we transition them to other G.M. dealers in the months ahead.”