Judge adds $184 million in interest to Apple's $634 million Masimo patent bill

Apple's bill in its long-running patent fight with Masimo just grew by $184 million. On Monday, October 5, US District Judge James V. Selna in California ordered Apple to pay that amount in prejudgment interest on top of the $634 million a jury awarded Masimo last November, Bloomberg Law reported. MacRumors, 9to5Mac, and AppleInsider have since followed.

That brings the total to roughly $818 million, and post-judgment interest will keep accruing until Apple pays.

Why the judge added interest

Apple argued that awarding interest would amount to a windfall for Masimo. Selna disagreed, citing US Supreme Court guidance that "interest from the time that the royalty payments would have been received merely serves to make the patent owner whole." Put simply, Masimo is being compensated for the years it went without royalties it should have collected.

Masimo didn't get everything it asked for. It wanted interest calculated at a 7% rate, which would have come to about $243 million. Selna instead used Masimo's own borrowing rate, compounded annually from when the infringement began, trimming roughly $59 million from Masimo's figure.

What the case covers

• The patent: US Patent No. 10,433,776, which covers a low-power approach to pulse oximetry. A jury found on November 14, 2025 that Apple infringed claims 11 through 14.
• The features: The verdict centered on Apple Watch features including heart-rate notifications and the workout mode, according to MacRumors and AppleInsider.
• The judgment: Selna entered final judgment for $634,313,913 on July 20, 2026, ruling that the infringement was not willful and the claims were not invalid. He kept the interest question open for further briefing, and that is what he has now decided.

The patent expired in June 2022, so the ruling concerns past Apple Watch sales only. It has no effect on the heart-rate features in current models. Apple has fought the award at each step so far, trying unsuccessfully to overturn or reduce it before Selna upheld the verdict in July.

A separate fight over blood oxygen

This damages case is distinct from Masimo's complaint at the US International Trade Commission, which led to a 2023 import ban on certain Apple Watch models. To keep selling those watches in the US, Apple disabled blood oxygen measurement on affected units sold there, then introduced a redesigned version of the feature in 2025.

For more on the lineup, see our Apple Watch coverage.

Sources

• Bloomberg Law, Annelise Levy, "Apple Owes $184 Million in Interest on $634 Million Patent Loss," October 5, 2026
• MacRumors, Tim Hardwick, "Apple's $634 Million Apple Watch Patent Bill Just Got Even Bigger," October 6, 2026
• 9to5Mac, Ben Lovejoy, "Apple must pay Masimo an extra $184M for Apple Watch patent infringement," October 6, 2026
• AppleInsider, Malcolm Owen, "Interest is making Apple's payout to Masimo much larger," October 6, 2026
• Masimo Corp. v. Apple Inc., final judgment, US District Court for the Central District of California, July 20, 2026