The US Treasury Bond market is one of the most liquid markets in the financial world.
Treasury Bonds are used to denote investor sentiment and are used as an indicator to the health of the economy. If bond prices rise we might see a slowdown of general economic activity.
If bond prices fall we might see a rise in interest rates. Bonds measure how well an investor thinks a country is doing; if the economy is booming there is less need for the Government to borrow money.
If we have a huge potential of default on corporate debts then bonds become more attractive for security.