By Kosaku Narioka

Advantest said it is responding to a ransomware cybersecurity incident that may have affected certain systems on its network.

The Japanese chip-testing equipment maker said Thursday it is working to determine the full extent of the incident while reinforcing its defenses.

Advantest said that if its investigation finds customer or employee data was affected, it will notify those individuals directly and provide guidance on protective measures.

The company said it detected unusual activity in its information-technology environment on Feb. 15, immediately activated its response protocols, isolated affected systems and engaged third-party cybersecurity experts to investigate and contain the incident.

Preliminary findings indicate an unauthorized third party may have accessed parts of the company's network and deployed ransomware, Advantest said.

The company's shares gave up earlier gains and were recently down 2.1% in Tokyo. The stock more than doubled last year and had risen 37% this year through Wednesday, driven by expectations for growing demand for chip testing.

Write to Kosaku Narioka at kosaku.narioka@wsj.com

(END) Dow Jones Newswires

February 18, 2026 21:53 ET (02:53 GMT)

Copyright (c) 2026 Dow Jones & Company, Inc.