A warrant that requires the holder to surrender a similar bond when purchasing a new fixed-income instrument. For the warrant to be exercisable, the two bonds must have similar terms, such as maturity, yield and principal.Also known as a "wedding warrant." 

|||Issuing a harmless warrant provides the debt issuer with some call protection. Under a normal warrant, bond holders might all opt to buy more instruments, drastically increasing the firm's level of debt. With a harmless warrant, the original bond must be surrendered at the time of purchase, allowing the level of debt to remain constant.