A former Wells Fargo advisor whose brother is suing the bank received private information about an estimated 50,000 clients and an undisclosed number of its registered representatives.

The news, reported by The New York Times late Friday includes the clients’ names, Social Security numbers, assets under management, portfolio performance and related data. One of the clients is “a well-known hedge fund billionaire who had at least $23 million invested through Wells Fargo Advisors,” the paper said.