A divided U.S. Supreme Court has given the go-ahead to an antitrust lawsuit accusing Apple Inc. of forcing consumers to overpay for iPhone software applications, a decision that could lead to billions of dollars in damages and put the company's lucrative way of selling apps at risk.

In a 5-4 ruling, the justices upheld a lower court's decision to allow the proposed class action lawsuit to proceed. The consumer plaintiffs claim Apple monopolized the market in violation of federal antitrust law by requiring that apps be sold through its App Store and extracting an excessive 30 percent commission on purchases.

Apple's shares fell 5.8 percent to $185.72 on Monday. The ruling came on a day when Apple shares already were trading lower because of concerns over a full-blown U.S.-China trade war.