Apple Owes Masimo $184 Million More for Watch Patents

A federal judge on October 5 added $184 million in interest to Apple’s $634 million Apple Watch patent bill. U.S. District Judge James V. Selna said the extra money covers royalties Masimo did not collect while Watch models used its patented low-power pulse oximeter method. Combined, Apple now owes about $818 million, and more interest runs until it pays.

The order is the cash half of a fight Apple already lost at the border. A separate trade case forced it to disable, then rebuild, blood oxygen on U.S. watches. This new sum is for past sales on an expired patent, and it is the bill for waiting.

Apple’s Watch Bill Climbs to About $818 Million

Selna ruled on Monday, October 5, 2026, in Masimo Corp. v. Apple Inc., case 8:20-cv-00048, in the Central District of California. A jury in November 2025 found that Apple Watch heart-rate notifications and workout mode infringed claims 11 through 14 of U.S. Patent No. 10,433,776. The jury set damages at $634 million. Selna entered final judgment in July 2026, denied Apple a new trial, and held that the infringement was not willful, so the award was not tripled.

Masimo then asked for prejudgment interest on that royalty. Apple called the request a windfall on top of what it already branded a staggering verdict. Selna said interest is how a patent owner is put back in the position a license would have created. He cited U.S. Supreme Court language that interest from the date royalties would have been paid does not enrich the owner. It fills the gap left by unpaid use.

THE BILL AFTER OCTOBER 5

• Jury royalty: $634 million awarded in November 2025 for Watch features that used the patented method.
• Prejudgment interest: $184 million, compounded yearly at Masimo’s own borrowing rate from when infringement began.
• Running total: about $818 million, before post-judgment interest that keeps accruing until Apple pays.
• Rejected ask: $243 million, which is what a flat 7 percent rate would have added.

Post-judgment interest is a separate meter. It ticks on the judgment until the check clears, including through an appeal. The $818 million figure is a floor, not a final invoice.

Masimo Asked for 7 Percent and Walked Away With Less

Masimo wanted the court to apply a 7 percent rate. That math would have put interest at $243 million. Selna refused. He used the rate Masimo itself pays to borrow, compounded annually from the start of the infringement period. Apple still owes $184 million. That is $59 million less than Masimo sought, and it is still a 29 percent add-on to the jury’s number.

That 29 percent is a share of the verdict, not a 29 percent yearly rate. The dollars piled up because the royalty was treated as late from the first Watch sales that used the method, then compounded year after year. A reader who sees $184 million next to $634 million and smells a penalty is looking at time, not a fine. Selna already declined to treat Apple as a willful infringer. Interest here is compensation for money Masimo did not have, not a multiplier for bad faith.

THE RATE FIGHT IN DOLLARS

Apple’s own damages theory at trial was $3 million to $6 million. The jury landed at the low end of Masimo’s range and nowhere near Apple’s. The interest order does not reopen that fight. It prices the delay after the fight was already lost.

The Low-Power Pulse Oximeter Patent Expired in 2022

The asserted patent is Masimo’s low power pulse oximeter patent, granted on October 8, 2019 to inventor Ammar Al-Ali and assigned to Masimo. The specification describes a pulse oximeter that cuts average power when the signal is quiet, then ramps sampling back up if noise rises or oxygen drops. Duty cycles as low as about 3.125 percent are part of that scheme. That is hospital-monitor thinking aimed at battery life, applied by the jury to a watch that pings heart rate all day.

The patent expired in June 2022. Selna’s cash ruling therefore covers historic Apple Watch sales. It does not require Apple to rip heart-rate alerts or workout mode out of watches on sale now. Apple has said the patent covers older patient-monitoring methods and that it will appeal the verdict. Because the term is over, winning or losing that appeal changes what Apple pays, not what a new Watch ships with.

Pulse oximeters shine red and infrared light through tissue and read the pulse in returning light. Heart rate is sitting in that same waveform. The jury treated certain Watch heart-rate notifications and workout functions as using Masimo’s low-power approach. That is why a blood-oxygen patent produced a verdict about heart-rate features, and why this case is easy to mix up with the import ban over on-wrist SpO2.

A Separate Ban Already Forced a Watch Redesign

The interest order is not the blood-oxygen fight most Watch owners remember. That fight ran at the U.S. International Trade Commission, on different patents, and it hit the product rather than the checkbook. In December 2023 the ITC issued a limited exclusion order against Apple Watch Series 9 and Ultra 2 models that infringed Masimo pulse-oximetry claims. Apple halted U.S. sales briefly, then shipped those models with blood oxygen turned off in software.

Joe Kiani, Masimo’s chief executive, called the earlier ITC finding a first step toward accountability and said it should help restore fairness in the market. Apple later built a workaround. From August 2025, sensor data from affected Series 9, Series 10, and Ultra 2 watches is sent to a paired iPhone for the blood-oxygen calculation. Results show up in the Health app, not on the Watch face. Apple said U.S. Customs cleared that design.

TWO TRACKS AGAINST THE APPLE WATCH

1. January 2020: Masimo and Cercacor Laboratories sue Apple in California federal court over patents and trade secrets.
2. December 2023: The ITC bars U.S. imports of Series 9 and Ultra 2 watches that still run the original on-wrist blood-oxygen design.
3. August 2025: Apple restores a redesigned reading that computes SpO2 on the iPhone after a Customs ruling.
4. November 2025: A federal jury awards Masimo $634 million on the separate ’776 patent for heart-rate notifications and workout mode.
5. March 19, 2026: An ITC judge finds the iPhone-side redesign does not infringe, while the Federal Circuit leaves the original exclusion order in place.
6. April 17, 2026: The full Commission declines review and closes the enforcement case, so the redesigned watches stay on the U.S. market.
7. July 2026: Selna enters final judgment, finds the infringement not willful, and denies Apple a new trial.
8. October 5, 2026: He adds $184 million in prejudgment interest.

Apple still cannot restore the original on-watch blood-oxygen display in the United States. The redesigned path is what U.S. buyers get. Watches sold before the ban, and units sold outside the United States, kept the older on-wrist flow. The $818 million does not buy that feature back. It prices a different patent that has already died of old age.

The 2020 Suit Grew From Talks in 2013

Masimo is an Irvine, California maker of hospital pulse oximeters, not a watch brand. Kiani has said Apple came to Masimo in 2013, under a confidentiality deal, to talk about putting the company’s methods into Apple products. Those talks ended. Apple then hired Masimo’s chief medical officer, Dr. Michael O’Reilly, and Cercacor’s chief technical officer, Marcelo Lamego, and later hired more people from both firms.

Masimo’s complaint, filed in January 2020 with Cercacor, accused Apple of taking secrets and infringing patents after those meetings. Apple has denied using Masimo’s inventions and has said it did not need a license. It also sued Masimo later, arguing Masimo’s own consumer watch copied Apple Watch design. The consumer product never became the story. The patents did.

By the time the jury sat in 2025, the live question was a royalty on Watch features, not a partnership. Apple’s $3 million to $6 million figure would have treated the method as a minor input. $634 million treats it as a core piece of the Watch’s always-on heart-rate system. $184 million then treats every unpaid year as a year Masimo should have been able to use that money. The 2013 meetings did not create that math. Shipping the feature without a license, then litigating into 2026, did.

Why Prejudgment Interest Is Not a Windfall

Patent damages sit in a short statute. After a win, the court awards damages plus interest under Section 284, at least a reasonable royalty for the use the infringer made, “together with interest and costs as fixed by the court.” Congress put interest in the text in 1946 so a winner is not paid in older, cheaper dollars.

The Supreme Court settled the standard in 1983. In General Motors Corp. v. Devex Corp., a unanimous Court said prejudgment interest should ordinarily be awarded so the owner stands where a timely royalty would have put him. Justice Thurgood Marshall wrote the opinion. Selna quoted that line back at Apple.

An award of interest from the time that the royalty payments would have been received merely serves to make the patent owner whole, since his damages consist not only of the value of the royalty payments but also of the forgone use of the money between the time of infringement and the date of the judgment.

Justice Thurgood Marshall, U.S. Supreme Court, General Motors Corp. v. Devex Corp.

That is the clause Apple’s windfall argument had to beat, and it did not. GM had made the same kind of plea decades earlier, after a long royalty fight over a metal-forming patent, and lost. Selna’s only real discretion was the rate and the compounding method. He used Masimo’s borrowing cost rather than 7 percent, which is how Apple avoided $59 million. He did not use a blank year. He compounded from when infringement began, which is how $184 million appears on a $634 million award without anyone calling it a 29 percent tariff.

WHAT SECTION 284 ACTUALLY ADDS

• The floor: A winner gets at least a reasonable royalty for the infringer’s use, not a bonus for winning.
• The interest: Ordinary prejudgment interest is meant to make the patent owner whole for royalties that arrived late.
• The limiter here: No willfulness finding, so no triple damages, and no 7 percent rate.

Apple can still argue on appeal that the jury’s royalty was wrong, or that the claims should never have reached a Watch. It cannot argue that a clean verdict gets no time value. That door closed in 1983.

Apple Plans to Appeal While the Meter Runs

Apple has said it will appeal the underlying $634 million verdict. The October 5 interest order raises the amount sitting under that appeal. Post-judgment interest keeps adding until Apple pays, which means delay is no longer free even if Cupertino likes its odds at the Federal Circuit.

Masimo did not get the 7 percent rate, and it did not get an injunction that would have pulled current heart-rate features. It got a paid-for delay on an expired patent, after a years-long ITC battle that already changed how U.S. watches read blood oxygen. Apple kept the product on sale, rebuilt the SpO2 path, and still faces an $818 million judgment that grows until the wire goes out.

The Watch on a U.S. wrist in 2026 already runs the workaround. The invoice from 2020 is what just came due.