From Bloomberg ...

U.S. regulators working to untangle Bernard Madoff's alleged $50 billion Ponzi scheme are probing other money managers suspected of using similar tactics, two people with knowledge of the inquiries said.

The U.S. Securities and Exchange Commission is pursuing at least one case in which investors may have been cheated out of as much as $1 billion, according to one person, who declined to name the manager and asked not to be identified because the probe isn't public.