(Yicai Global) Oct. 25 -- Shares of Cathay Pacific Airways lost 3.8 percent today after the Hong Kong carrier admitted a data breach more than half a year after the fact.

Hackers stole data on 9.4 million passenger, including passport and credit card details, the Hong Kong-listed company said in a press release yesterday. Cathay Pacific discovered the unauthorized access to its information system in March.

Cathay Pacific said it ensured that the incident did not harm flight safety and has no evidence that any personal information has been misused. "The company took immediate action to contain the event, to commence a thorough investigation with the assistance of a leading cybersecurity firm, and to further strengthen our information system security measures," it said.

The company's shares [HKG:0293] ended today at HKD10.22 (USD1.30), after earlier dropping almost 7 percent. The benchmark Hang Send Index lost just over 1 percent.

The leaked data may include passenger names, nationalities, dates of birth, telephone numbers, email addresses, residential addresses, identity card numbers, and flight history. Some 403 expired credit card numbers and 27 valid credit card numbers with no CVV numbers were accessed.

The firm is contacting affected passengers and providing suggestions on how to secure their personal information. The company has also notified the Hong Kong Police.

Editor: Emmi Laine