The lawsuit in U.S. District Court accused Wal-Mart Stores Inc. of violating federal and state wage laws. The jury did not rule on monetary damages, which will be decided in a separate trial.

More than 400 employees from 24 of Wal-Mart's 27 Oregon stores sued the retailer. It was the first of several similar suits across the country to come to trial.

Wal-Mart attorney Rudy Englund had no comment on the verdict and referred all questions to Wal-Mart headquarters in Bentonville, Ark.

The suit was filed by Carolyn Thiebes and Betty Alderson, who worked in managerial positions at Wal-Mart stores in the Salem area.

The suit claimed managers got employees to work off the clock by asking them to clean up the store after they'd clocked out and by deleting hours from time records.

It also said Wal-Mart reprimanded employees who claimed overtime. Workers felt forced to work after clocking out because managers assigned them more work than they could complete in an regular shift, the plaintiffs said.

Englund conceded during opening arguments Tuesday that some off-the-clock work occurred, but said company policy expressly forbid it.

Wal-Mart, a $218 billion company, employs a million workers in 3,250 stores in the United States.

The verdict was released after the close of markets. Wal-Mart Shares finished the day down 22 cents at $50.16 on the New York Stock Exchange

Attorneys said the verdict could determine the fate of 39 other class-action lawsuits pending against the company in 30 states. Those suits, spread from California to New York, involve hundreds of thousands of workers seeking tens of millions in back pay.

Previously, Wal-Mart settled two similar overtime cases in Colorado and New Mexico.

The company reportedly paid $50 million two years ago to settle an off-the-clock lawsuit covering 69,000 workers in Colorado, and it recently settled for $500,000 a case involving 120 workers in Gallup, N.M., said one of the plaintiff's attorneys.