Gives the buyer the right, but not the obligation, to buy or sell an asset at a set price on or before a given date. Investors, not companies, issue options. Buyers of call options bet that a stock will be worth more than the price set by the option (the strike price), plus the price they pay for the option itself. Buyers of put options bet that the stock's price will drop below the price set by the option. An option is part of a class of securities called derivatives, which means these securities derive their value from the worth of an underlying investment.