Ask Matt: Stocks most likely to be booted from S&P 500?

— -- Q: Which stocks are the most likely to get kicked out of the Standard & Poor's 500 index?

A: Investors try to guess which stocks might be added to the benchmark Standard & Poor's 500. But you rarely hear about the other direction.

Investors try to predict which stocks might be added to the S&P 500 because there's big money to be made if they're right. After a stock is added to the S&P 500, billions of dollars that are invested in indexes and funds that track the index must buy the stock. Imagine buying a stock that millions of other investors must buy after you do. It's pretty common for stocks to post gains after being added to the popular index.

But on the other hand, getting kicked out of the S&P 500 is a badge of dishonor. The index is designed to capture the value of large U.S. companies. Being part of the S&P 500 gives companies a kind of seal of approval regarding their size. Therefore, getting the boot is a blow, at least in the eyes of investors.

To be entirely clear, there's no way to know for sure which stocks will be removed from the S&P 500. The investment advisory group at S&P Dow Jones Indexes periodically reviews the members of the S&P 500 and makes changes several times a year.

There are many criteria that the S&P 500 selection committee takes into consideration. But given that the index is designed to measure the largest U.S. stocks, it's a safe assumption that companies with the lowest market values would be subject to review.

Below is a list of the members of the S&P 500 with the lowest market values. Again, this is not a list of stocks that are being removed from the index. These stocks may be left in the S&P 500 based on criteria other than market value. But, still, it's a list of stocks that will certainly get the attention of the S&P 500 committee.

Ten least valuable stocks by market value (in billions) in the S&P 500, according to S&P Capital IQ:

Matt Krantz is a financial markets reporter at USA TODAY and author of Investing Online for Dummies and Fundamental Analysis 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. Follow Matt on Twitter at: twitter.com/mattkrantz