An issue with a put provision included in the agreement grants the bondholder the right to sell bonds back to the issuer at a pre-specified rate and date. The specified rate is known as put price. Normally the put price is equal or close to the par value of the bond. However, in zero coupon bonds put price is less than the par value. When market interest rate rises above the coupon rate, then the bondholder uses his right under the put provision and forces the issuer to redeem the bond at the put price. He can then invest the proceeds form the bonds in higher interest rate instruments.