For example, let's assume that a stock is trading at $30. An option investor has purchased one call option with a strike price of $35 for a premium of $0.50 and sold one call option with a strike price of $30 for a premium of $2.50. If the price of the underlying asset closes below $30 upon expiration, then the investor collects $200 (($2.50 - $0.50) * 100 shares/contract).