A bond market index is a method of measuring value of a portion of the bond industry. It is computed on the prices of picked bonds. It is a tool used simply by investors and financial managers to explain the market, and compare the give back on specific investments. A bond market index is a mathematical construct, so it will not be invested in specifically. But many common funds and exchange traded funds seek to “track” an catalog, and those funds that not may be judged against those that do.