Facebook's initial public offering was May 18. CNBC was covering the event live. Ian went online at 11 a.m. Shares were selling at $39 each. He decided to gamble his entire savings of $5,000. He placed a market order to buy 128 shares. He waited for the order to fill. Then he remembered something. If the share price increased, he would have to pay the higher price. There is no maximum price per share for a market order. He should have placed a limit order. A limit order sets a maximum price per share. He clicked on a button to cancel his order. His computer screen displayed Cancel Pending. He called his stockbroker. The representative listened to Ian's problem. She said, "If your order fills first, the cancel won't apply. If the share price doubles later today, you might owe another $5,000. Next time, use a limit order. Good luck."