MasterCard reportedly reached a settlement with

Wal-Mart

(WMT) - Get Report

and other retailers over debit-card practices.

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The announcement by U.S. District Court Judge John Gleeson came just as the trial was set to begin, media reports said. The decision left Visa as the remaining defendant in the case.

Judge Gleeson prohibited all the parties involved to discuss the details of the agreement publicly.

The case centers on how retailers process purchases made with debit cards. Retailers say that MasterCard and Visa have been charging unjustifiably high fees for these transactions, and the stores were suing for billions of dollars, accusing the companies of antitrust violations in the quickly-growing U.S. debit-card market.

Together, the companies control almost four-fifths of the credit card business, with practically half of it in the hands of heavyweight Visa.