Online foreign exchange trading firm FXCM says it has been the victim of a hacking attack that exposed access to sensitive customer information and led to unauthorised transfers from "a small number" of client accounts.
FXCM says it has notified the FBI of the incident after receiving an e-mail from a hacker who claimed to have cracked the company's computer defences and downloaded client details.
The company says it has hired a cybersecurity firm to conduct "an extensive forensic investigation to determine the scope of the incident and identify affected customers".
It states that all stolen funds have been repatriated to customer accounts and has mandated a password reset for all users.
FXCM recorded retail customer trading volume of $329 billion from almost 600,000 trades and $47 billion in institutional trading volume in August 2015. The firm claims to have over 180,000 active trading accounts.
In a statement, the company says: "FXCM takes the privacy and security of our customer information very seriously and we are dedicated to protecting that information. As we learn more, we will continue to provide updates."