Apollo said it suffered a cyber attack last month in which hackers appeared to have gained unauthorised access to personal data on its systems, making it the latest Wall Street group targeted in a wave of attacks. The private equity group said an investigation determined there had been unauthorised access to "certain cloud platforms" between July 6 and July 10, and that it had notified law enforcement of the breach.

In a letter posted to the website of California's attorney-general on Friday, Apollo said it learnt on July 12 that the information included names, dates of birth, home addresses and social security numbers. It blamed a "social engineering incident", referring to a situation where attackers trick people in order to unlock secure systems, such as with phishing emails or deceptive phone calls. Apollo did not disclose details of the incident.

The letter said there was no evidence of personal information being "publicly posted or used for identity theft or fraud at this time".

Earlier this month, several hedge funds including Steve Cohen's Point72, Ken Griffin's Citadel and Millennium Management were revealed to have been targeted in cyber attacks. Apollo did not immediately respond to a request for comment.