Apple's $818 Million Masimo Bill: Old Patent, No Change to Your Watch

MacRumors reports that a federal judge has added $184 million in interest to the $634 million Apple already owes medical device company Masimo for patent infringement, pushing the total bill to around $818 million. U.S. District Judge James Selna rejected Apple's argument that the extra interest constituted a windfall for Masimo.

"Interest from the time that the royalty payments would have been received merely serves to make the patent owner whole."

— Judge James Selna, citing U.S. Supreme Court guidance

Masimo had asked the court to calculate interest at a 7 percent rate, which would have added $243 million, but Selna instead used Masimo's own borrowing rate, compounded annually from the start of the infringement. That brought the interest figure to $184 million.

The case stems from a November 2025 jury verdict finding that Apple Watch heart-rate notifications infringed a Masimo pulse-oximetry patent. Apple tried to overturn or reduce the award, but Selna upheld the verdict in July.

Masimo is also behind a separate patent dispute that led to a U.S. import ban on certain Apple Watch models, forcing Apple to disable the blood oxygen feature on affected new watches. Apple introduced a redesigned version of that feature in 2025.

The patent in question expired in June 2022, so the ruling covers only historical Apple Watch sales. Nothing here affects the heart-rate or blood oxygen features in current models.

If you own an Apple Watch, your heart-rate sensor isn't changing. If you're shopping, the blood oxygen drama of 2024 is the bigger story, and Apple already addressed it last year. This $818 million is Masimo's win, not your problem.

• Apple
• Apple Watch
• federal court
• Masimo
• patent infringement
• pulse oximetry