Average daily trading volume of U.S. treasury securities 2000-2018
What are treasury securities?
Treasury securities are U.S. government debt, bonds sold to finance the United States government. Since the United States is seen as a guaranteed investment, these bonds are often used by large financial firms as collateral. The yield on a Treasury bond is minimal, but these institutions often do not hold them until maturity, instead trading them on secondary market.
Other options
The federal funds rate is the rate the Federal Reserve charges banks for overnight loans. Other assets, such as mortgaged backed securities, can also be used like treasury securities. Mortgage backed securities are bundles of home loans packaged together. Such bundling makes the overall security safer, unless there is a systemic shock to the housing market which would undermine the entire package.