If you tell your broker to sell a stock, consider it gone

— -- Q: Let's say you call your broker to sell your stock in the morning, when it's trading for $10 a share. What price do you get if the stock closes at $9?

A: When you tell your broker to sell like that, they must execute your order right away.

With stocks listed on stock exchanges, like the New York Stock Exchange and Nasdaq, your order hits the marketplace pretty quickly. Brokers are required by law to check all the major market makers to get the best price or so-called "execution." Market makers in a stock may include other brokerage firms, trading desks or firms that buy and sell stocks on the NYSE's trading floor.

And that's it. If you sell, you sell quickly. Just remember, there's always a "bid" price and an "ask" price on a stock. The bid is the price at which a buyer is willing to buy shares, and this would be the price you would get. The ask is the price a seller is asking of someone who wants to buy the stock. Generally, the bid price is a bit lower than the ask. The "spread" between the two is to compensate the market maker for the risk it is taking.

Matt Krantz is a financial markets reporter at USA TODAY and author of Investing Online for Dummies. He answers a different reader question every weekday in his Ask Matt column at money.usatoday.com. To submit a question, e-mail Matt at mkrantz@usatoday.com. Click here to see previous Ask Matt columns.