portland non profit organizations , BMO capital markets of U.S. rates strategy director Ian Lygen is described: "we believe that prices change due to interest rate debt investors don't want to stand in front of a sell-off on the eve of the end of catch a falling knife." Interest rate, in the form of expression, refers to the ratio of the amount of interest to the total amount of borrowed capital in a certain period of time.  the interest rate is the interest level per unit time of the unit currency, indicating the interest rate. Economists have been looking for a theory that can fully explain the structure and change of interest rates. Interest rates are usually controlled by the central bank of the country and administered by the federal reserve board in the United States. Today, interest rates are one of the important tools for macroeconomic regulation. Investment in securities is conducive to adjusting capital investment and improving the efficiency of capital use, thus guiding the rational flow of resources and realizing optimal allocation of resources.