There is probably the US Exchange Stabilization Fund too, but this is from the horse's mouth:
The Shadow Banking System
During a crisis, liquidity pressures can materialize in the shadow banking sector--that is, the set of nonbanks that use a range of markets and instruments to provide financing to borrowers. At the time of their initial difficulties, both Bear Stearns and Lehman Brothers were in the shadow banking system.
To help improve the resiliency of this sector, a few new regulations have been introduced...