A warrant to purchase a company's stock is very similar to a listed call option, but has greater complexity.

At its core, a warrant is basically a call option with a longer life. However, while an American-styled option can be called at any time, there are various types of provisions restricting an issuing company's ability to call a warrant. In addition, while there is a chain of options at varying strike prices, most warrants stand alone - being the only such security issued by the company.