(Reuters) - Investment bank Morgan Stanley's ( MS ) wealth management arm is being probed by multiple regulators, the Wall Street Journal reported on Thursday citing people familiar with the matter.

The U.S. Securities and Exchange Commission, the Office of the Comptroller of the Currency (OCC) and other Treasury Department offices are involved, the report said. Shares of the bank fell 4.4% to $87.71.

Morgan Stanley's ( MS ) wealth management unit caters to high net-worth individuals and small to medium-sized businesses, providing them with brokerage, custody, investment advisory and financial planning services.

The business is more insulated from seismic shifts in the market compared to investment banking and has been a crucial factor in determining the premium valuation Morgan Stanley ( MS ) commands relative to rival Goldman Sachs.

The main issues under the scanner were whether the bank has been sufficiently investigating the identities of prospective clients and where their wealth comes from, and how it monitors their financial activity, the report said.

Some of the probes are also focusing on international clients, the report added.

Morgan Stanley ( MS ) had only recently resolved a years-long investigation into its block trading practices.

Spokespeople for Morgan Stanley ( MS ), the SEC, the OCC and the Treasury did not immediately respond to Reuters' requests for comment.