Debt securities are negotiable financial instruments serving as evidence of debt. Main features of debt securities are: issue and redemption date, issue and redemption price as well as a coupon rate that the issuer pays to the holders of the debt securities. The coupon may be fixed throughout the lifetime of the debt security or vary with inflation, interest rates or asset prices. Zero-coupon debt securities offer no coupon interest. Examples for debt securities are bonds, federal treasury bills, commercial papers, registered bonds, covered bonds and municipal bonds with a fixed regular income.