The federal funds rate is the interest banks charge each other for overnight loans. Set by the Federal Reserve, it's a basis for other interest rates.

Some forecasters expect the Fed to cut interest rates by a quarter-point Wednesday. Most, however, expect a half-point reduction. The CME FedWatch forecast tracker favored a half-point cut by a 55-45 margin at midday. (Earlier Wednesday, forecasters rated the probability of a half-point reduction even higher.)

The Fed's decision will lower borrowing costs from a 23-year high as the central bank pivots to shoring up economic growth.