One of the riskiest investment strategies in the financial world involves selling stock short. This involves borrowing stock from your broker and selling it. If the stock's market price drops, you can buy it back at the lower price, pay back your broker and pocket the difference. Problems arise if the stock price doesn't co-operate and instead skyrockets. You can hedge your position by buying protective call options.
A call option gives the option holder the right, but not the obligation, to purchase the underlying security at a fixed price, called the strike price, for a set period. If the option isn't exercised before it reaches its expiration date, it becomes worthless and ceases to exist. Call options are traded on major investment exchanges in much the same way that stocks are traded. While owning a call option doesn't give you ownership of the underlying stock, it does give you control over that stock for as long as the option is in force.