Apple Watch: Masimo patent dispute now costs Apple $818 million

Apple's patent dispute over the Apple Watch has become considerably more expensive. Bloomberg Law reports that federal judge James V. Selna ordered Apple on October 5 to pay medical technology company Masimo an additional $184 million in interest. The order follows a November 2025 jury verdict awarding Masimo $634 million in damages. That brings the total to roughly $818 million, with further interest potentially accruing until Apple pays.

Apple argued that interest would give Masimo an unwarranted windfall. The judge disagreed, citing Supreme Court guidance: interest dating back to when royalty payments would have been due simply puts the patent holder in the position it would have been in had it received the money on time. Masimo did not get everything it sought, however. Selna rejected its requested 7% interest rate and instead used Masimo's own borrowing costs, compounded annually. At 7%, the interest would have totaled roughly $243 million.

Patent expired in 2022

Why is Apple paying over a patent that expired four years ago? Patent No. 10,433,776 covers a low-power pulse oximetry technique and expired in 2022, so the case concerned past sales. The jury accepted Masimo's argument that the Apple Watch, with its heart rate notifications and workout mode, qualifies as a "patient monitor" under the patent. Apple argued unsuccessfully that the term referred to conventional medical equipment rather than a smartwatch. Its request for a new trial was also denied.

Nothing changes for current buyers, as the ruling does not affect any current features. This is also a separate case from the dispute before the US trade agency ITC over blood oxygen measurement, which Apple won in April. Apple has said it will appeal, noting that Masimo asserted more than 25 patents, most of which were declared invalid.

Costly weeks in US courts

An $818 million bill will not destabilize Apple, but it is hardly pocket change. The broader context is more interesting: in late September, a San Diego jury awarded $5.7 billion in damages against Apple over the Taptic Engine. Whether appeals ultimately reduce those amounts remains uncertain. What is clear is that, after more than six years, the dispute with Masimo is still not over.