Bond Investments are issued by a borrower, such as a public entity or corporation, that seeks to raise funds. The borrowing entity promises to repay the face amount by a set maturity date and may pay interest at regular intervals, which can accumulate over time. Bond values may fluctuate with changes in interest over time, but this will not change the issuer's obligations to repay the principal amount at maturity. There are different types of bond investments: U.S. government bonds, municipal bonds, corporate bonds and bond mutual funds.