The Federal Reserve Bank of New York added $87.7 billion to the financial system Tuesday, using the market for repurchase agreements, or repo, to relieve funding pressure in money markets.

Banks asked for $67.6 billion in overnight reserves, all of which the Fed accepted, offering collateral in the form of Treasury and mortgage securities.

In a separate operation, banks asked for $20.1 billion in 14-day loans, all of which was accepted by the Fed, offering collateral in the form of Treasury and mortgage securities.

In the repo market, borrowers seeking cash offer lenders collateral in the form of safe securities—frequently Treasury bonds—in exchange for a short-term loan. The term of these loans can be as short as overnight.

When the Fed adds money to the financial system through the repo market, it is acting as a lender. In typical repo market transactions, lenders can include money-market mutual funds, banks or hedge funds that are seeking to earn a slightly higher rate of interest than what is available from holding very short-term government securities. The borrowers are often banks, securities firms or hedge funds that use the cash to finance positions in the market.