The Federal Reserve Bank of New York added $49.7 billion to the financial system Monday, using the market for overnight repurchase agreements, or repo, to relieve funding pressure in money markets.

Banks asked for $49.7 billion in overnight reserves, offering collateral in the form of U.S. Treasury and mortgage securities. The New York Fed had offered to add at least $75 billion daily to the financial system through Oct. 10.

Rates...