Each Federal reserve bank will ascertain whether undue use is being made of Bank Credit.

http://en.wikipedia.org/wiki/Federal_Reserve_System

This policy is described in United States Code:-

Each Federal reserve bank shall keep itself informed of the general character and amount of the loans and investments of its member banks with a view to ascertaining whether undue use is being made of bank credit for the speculative carrying of or trading in securities, real estate, or commodities, or for any other purpose inconsistent with the maintenance of sound credit conditions; and, in determining whether to grant or refuse advances, rediscounts, or other credit accommodations, the Federal reserve bank shall give consideration to such information.