Apple’s $634 million Apple Watch patent loss has become considerably more expensive.
A federal judge has ordered Apple to pay Masimo another $184 million in prejudgment interest, bringing the judgment to about $818 million before additional interest continues to accrue until it is paid.
That extra $184 million adds nearly 29% to the original jury award.
Why Apple owes another $184 million
The additional money accounts for the years Masimo went without royalty payments the jury determined it should have received.
Apple argued that adding prejudgment interest would give Masimo a windfall. U.S. District Judge James Selna disagreed, finding that compensating Masimo for the time it was deprived of those royalties serves to make the company whole.
Masimo had sought even more. It asked the court to calculate interest at 7%, which would have added roughly $243 million.
Selna instead used Masimo’s borrowing rate and compounded the interest annually from when the infringement began.
Post-judgment interest is also accruing, meaning the amount can continue climbing while the judgment remains unpaid.
This won’t change your current Apple Watch
The underlying case concerns a Masimo pulse-oximetry patent and Apple Watch features including heart-rate notifications. A jury found in November 2025 that Apple infringed the patent and awarded Masimo $634 million in damages.
The patent expired in June 2022, so the case covers older Apple Watch sales rather than the watches Apple sells today. This ruling isn’t changing or removing current heart-rate features.
Apple’s fight with Masimo over blood oxygen is a separate patent dispute. That case produced the U.S. import restrictions that forced Apple to disable blood oxygen functionality on newly sold watches before introducing a redesigned version of the feature in 2025.
The two cases show how expensive the long-running dispute has become in different ways. One forced Apple to redesign a major Apple Watch health feature; the other has produced a judgment now worth more than $818 million, with Apple’s appellate options still available.
