The U.S. District Court for the Central District of California had previously sided with Masimo in late 2025, saying Apple infringed on four biosensor patents after a years-long, back-and-forth legal battle that included import bans on certain Apple Watches offering the blood oxygen tracking feature.
The ruling earlier this week agreed with Masimo’s argument that it deserves prejudgement interest covering the time period when Apple should have made a royalty agreement — in this case, starting in January 2020 and then compounding annually.
While Apple argued against paying interest, saying the jury’s original award was generous enough to be “staggering” and that an extra nine figures would be a windfall, Masimo countered by saying that not paying would instead deliver a windfall to the tech giant, which posted $416 billion in net sales for its 2025 fiscal year. Meanwhile in June, Danaher completed its $9.9 billion acquisition of Masimo.
The two parties also debated the appropriate rate, with Masimo initially seeking the 7% set for prejudgement interest under the California constitution, which would have totaled $242.7 million. Apple said it should follow the lower Treasury bill rates that spanned the COVID-19 pandemic years, amounting to $114.5 million.
Instead, the court went with a calculation put forward in testimony by one of Apple’s own experts during the trial, which determined Masimo’s cost of borrowing money during that time. The final tally came to $184,189,784, bringing the case’s total up to $818.5 million.
Additionally, Apple has been ordered to pay postjudgement interest, as required by law, on any late future payments at an undisputed 4.02% rate.
