Olympus shares fell sharply in Tokyo on Wednesday. The Japanese company makes endoscopes and other medical devices. It had just disclosed a warning letter from the U.S. Food and Drug Administration.

By mid-morning in Tokyo, the stock was down 16.5%. That was its lowest level since July 1, Nikkei reported.

The FDA letter is dated Oct. 7, MassDevice reported. It follows inspections late last year at six sites in Japan, Germany and the U.S., the trade outlet said. The letter takes issue with how Olympus responded to quality system violations that inspectors had flagged in 2025.

The inspected sites include endoscope production facilities in Japan, a subsidiary in Hamburg, Germany, and Gyrus ACMI, a Minnesota toolmaker Olympus bought in 2008, MassDevice reported. As of its report, the letter had not yet been posted to the FDA's public database.

The warning does not limit Olympus' ability to make, sell or distribute its products, and it does not call for any recalls, MassDevice reported. Olympus said it is working on a response to the FDA this month and will send regular updates after that.

"We take the concerns identified in the warning letter seriously and are fully committed to resolving these matters with urgency and rigor," CEO Bob White said in a statement, MassDevice reported.

The FDA has taken action against the company before, MassDevice noted. In mid-2025, the agency warned health care providers about import alerts on some Olympus devices made in Japan. In January, Olympus recalled some older insufflation units, which the FDA later placed in its most serious recall class.

What we know: Olympus shares dropped as much as 16.5% after it disclosed the FDA warning letter.
What we don't: Whether the FDA will accept the company's planned response and corrective steps.