Warrants are sold by companies as a way to raise capital. Although a company could sell stock to raise money, the Securities and Exchange Commission regulates the number of shares a company is allowed to issue. Some companies will issue warrants as a way to sweeten a deal during a takeover or restructuring.
How do I exercise them? Most stock warrants are similar to call options in that they provide the holder the right, but not the obligation, to buy shares of a company at a specified price (strike price) before the warrant expires. Unlike an option, a warrant is issued by the company instead of an option writer.