What do you mean by this? As far as I know, the Fed was established by an Act of Congress and it is overseen by a Board of Governors whose members are appointed by the President and report to the Congress. To me it doesn't necessarily seem too different from many other government agencies, the biggest difference being that it is self-funded.

Because of its autonomy it doesn't seem to fall well within any of the three classical branches of government, but it sure seems to me like a part of the government nonetheless.