The Federal Reserve has auctioned more than $7bn in securities, which it hopes that it will boost the credit markets.
The Federal Reserve last year started a succession of auctions to help shore up liquidity after the credit crunch. The central bank is hoping to stop the housing slowdown from turning into wider recession.
In exchange for the securities, investment firms can obtain a short-term cash loan by trading it with their more risky investments, including mortgage backed risks.
It is hoped that when financial firms take out the short-term loans from the Federal Reserve, they can then lend more money to each other, making it far easier to lend to consumers.