The New York branch of the U.S. Federal Reserve added billions more in liquidity to gummed-up intrabank lending markets Wednesday, following the first intervention in more than a decade only yesterday, as a worrying spike in overnight borrowing costs continues to perplex investors and complicate today's Fed rate decision.

The New York Fed offered $75 billion in cash to broader markets, in exchange for eligible collateral such as U.S. Treasury bonds or mortgage-backed securities, in order to hold the Fed's key rate inside its target range of between 2% and 2.25%. It accepted its full allotment, even as bids totaled $80 billion, lowing the range from 2.6% to 3% prior to the operation to 2.25% to 2.6% immediately afterwards.