Apple on Thursday stopped online sales of two popular models of its internet-connected watch in the U.S. after losing its latest attempt to untangle a patent dispute that's blocking it from using some of the technology on the device.

Both the Apple Watch Series 9 and Ultra 2 became unavailable to order online beginning at 3 p.m. ET, as the company followed through on its plan to suspend sales of them because of a legal battle over an intellectual property claim filed by medical technology company Masimo.

The International Trade Commission on rejected Apple's bid to get around a late October order blocking the company from using some of technology underlying the Blood Oxygen measurement feature on the Series 9 and Ultra 2 watches.

Stymied by the decision, Apple decided to stop to stop selling the two watch models in the U.S. to comply with the ITC ruling that will now stand, unless the Biden administration overturns it by Christmas.

Although the online sales suspension went into effect Thursday afternoon, the devices are scheduled to remain on store shelves until Sunday. The less sophisticated Apple Watch will remain available in the U.S. after Christmas Eve. Previously purchased Apple Watches equipped with the Blood Oxygen aren't affected by the ITC order.

Wedbush Securities analyst Dan Ives estimates Apple's holiday-season sales will be reduced by $300 million and $400 million if the patent dispute results in the two watch models being pulled from the U.S. market during the final week of the year.

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