A warrant is a security issued by a company that allows the owner to redeem the warrant for shares of stock in the company at a predetermined price. Like an option, a warrant can be traded on an exchange. Unlike a stock option, a warrant can have a very long duration to expiration, even more than a decade, or no expiration at all. Warrant that never expires is called a perpetual warrant, and a warrant that expires on a specific date is called a subscription warrant. A stock-purchase warrant is an alternative term.