Judge Orders Apple to Add $184 Million Interest to Masimo Patent Verdict

A federal judge has upheld a $634 million patent infringement judgment against Apple and added $184 million in prejudgment interest, bringing the total bill to approximately $818 million. The ruling stems from Masimo's pulse-oximetry patent claims related to Apple Watch heart-rate monitoring features, with the judge rejecting Apple's argument that the interest would constitute a windfall. The patent in question expired in June 2022, so the judgment affects only past Apple Watch sales and does not impact current models.

The financial penalty stems from Apple's incorporation of heart-rate monitoring capabilities in its smartwatch that allegedly duplicated technology protected by Masimo's pulse-oximetry patent. A jury determined in late 2025 that Apple's implementation infringed on the medical device maker's intellectual property rights, leading to the initial $634 million award. Judge Selna's decision to add interest reflects judicial reasoning that patent holders deserve compensation for the period during which they were unable to collect licensing fees they would have legitimately received.

This represents one of several ongoing disputes between the two companies. Masimo has pursued parallel legal action resulting in import restrictions on certain Apple Watch models, prompting Apple to modify the blood oxygen measurement feature across affected devices and subsequently redesign the functionality in 2025.