Hundreds of wealth management clients of Wall Street giant Morgan Stanley had their account information stolen and posted on the Internet by a former employee.

The New York City-based firm says that approximately 900 clients, representing 10% of its client base, had their account information, including account names and numbers, posted on the Internet. The stolen data does not include account passwords or social security numbers, the firm reports, and it says that there’s no evidence of any economic loss to clients as a result. “Morgan Stanley detected this exposure and the information was promptly removed,” it says.

In the meantime, the affected clients are being contacted by the firm and their advisors to alert them to the security breach. A pair of dedicated information lines have been set up for clients, one for clients in the U.S. and Canada, and another line for clients in the rest of the world. The firm says that it’s also instituting enhanced security procedures including fraud monitoring on these accounts.

The employee that allegedly committed the breach has been terminated, “and law enforcement and regulatory authorities have been advised of the incident,” the firm says. “Morgan Stanley takes extremely seriously its responsibility to safeguard client data, and is working with the appropriate authorities to conduct and conclude a thorough investigation of this incident.”