DETROIT —  General Motors Corp. (GM), the world's biggest automaker, is ending its popular discount program that let buyers pay the same price its employees pay for vehicles throughout the summer.

The promotion was scheduled to end Friday at the close of business for each dealer, GM spokeswoman Deborah Silverman said.

GM introduced the incentive in June and originally planned to end it in July, but it proved so popular that the company extended it several times. GM's U.S. sales shot up 41 percent in June and 19 percent in July. The discount was in place on most 2005 vehicles as well as some 2006 full-size trucks and sport utility vehicles.

Ford Motor Co. (F) and DaimlerChrysler AG's (DCX) Chrysler Group matched the program in July. Both automakers plan to end their employee incentives on Monday.

Analysts are predicting a sales hangover for U.S. automakers this fall, since the discounts depleted 2005 inventories and accelerated sales to the summer. GM's U.S. sales fell 16 percent in August and are expected to fall even farther in September. Automakers report September sales on Monday.

GM is trying a new pricing strategy with its 2006 models. The automaker has lowered overall prices and hopes to rely less on incentives going forward. GM's incentives can approach $4,000 per vehicle, and the company said that makes it difficult for consumers to figure out what they would actually pay.

GM shares fell 31 cents to $30.38 in morning trading on the New York Stock Exchange. Its shares have traded in a 52-week range of $24.67 to $43.29.