Judge adds $184m in interest to Apple’s Apple Watch patent bill, taking it past $818m
The case turned on whether a smartwatch with heart-rate alerts counts as a “patient monitor”. Apple says it will appeal, and current watches are not affected.
A US federal judge has ordered Apple to pay Masimo $184.2 million in interest on top of the $634 million a jury awarded the medical-technology company in an Apple Watch patent case, bringing the total to about $818.5 million.
Judge James V. Selna of the US District Court for the Central District of California issued the order on 5 October, Bloomberg Law reported.
How the interest was calculated
Prejudgment interest compensates a patent holder for money it should have received earlier. Apple argued that adding it would be a windfall for Masimo. The judge disagreed, citing Supreme Court guidance that “interest from the time that the royalty payments would have been received merely serves to make the patent owner whole”, according to Bloomberg Law.
The two sides were far apart on the rate. Masimo asked for 7%, the rate set by the California Constitution, which would have produced $242.7 million, MedTech Dive reported. Apple proposed a rate that would have produced $114.5 million. The judge chose Masimo’s own borrowing cost, compounded annually from when the infringement began, which gave $184.2 million.
Apple must also pay post-judgment interest of 4% on the $818.5 million from 20 July until the judgment is paid, according to MedTech Dive, which said Apple did not dispute that part.
What the case is about
The jury verdict came in November 2025. It concerned a single Masimo patent, US 10,433,776, titled “Low power pulse oximeter”, which Google Patents lists as expired in 2022. The case therefore concerns past sales, and Notebookcheck reported that it does not affect any features on current watches.
Much of the trial turned on whether the Apple Watch counts as a “patient monitor” under the patent’s wording. According to 9to5Mac, Masimo pointed to the watch’s high heart-rate notification to argue that it does. Apple countered that the alert only activates after the wearer has been still for at least 10 minutes, and that patient monitors are designed for continuous monitoring. The jury sided with Masimo.
9to5Mac reported that the verdict covered 43 million Apple Watch units sold with the feature. Apple had argued that damages should be between $3 million and $6 million; Masimo sought between $634 million and $749 million.
What Apple and Masimo said
After the verdict, Masimo called it a “significant win in our ongoing efforts to protect our innovations and intellectual property”, 9to5Mac reported. Apple said Masimo had “sued Apple in multiple courts and asserted over 25 patents, the majority of which have been found to be invalid”, and that the patent at issue was “specific to historic patient monitoring technology from decades ago”. Apple has said it plans to appeal.
Masimo is no longer an independent company. Danaher, the US healthcare group, completed its $9.9 billion purchase of Masimo in June 2026, and Masimo now operates as a subsidiary under its own brand, Respiratory Therapy and MedTech Dive reported.
Why it matters for wearables
For athletes, the case changes nothing on the wrist. Its significance is in the line it draws. Consumer watch makers increasingly sell health alerts, from heart-rate warnings to blood pressure trends, while describing them as wellness features rather than medical ones. In this case, a jury accepted that a sports watch with a heart-rate alert could fall within the wording of a patent written for clinical monitoring equipment.
The dispute between the two companies has now run for more than six years, Notebookcheck noted, and an appeal means it is not yet over.
