Rising tide has lifted most boats, but these stocks sank

— -- Q: Is it possible for some stocks to have fallen in value since March 9, even though the Standard & Poor's 500 stock index is up sharply from that time?

A: You've surely heard the cliché that a rising tide lifts all boats. Well, in investing that's not always true.

Certainly, most stocks have enjoyed a huge upswing from their March 9 lows. The Standard & Poor's 500 index, a broad measure of the largest U.S. stocks, has jumped almost 50% from its low point this year, which was 676.53 on March 9.

But just because the stock market goes up, doesn't mean all 500 stocks in the S&P 500 stock index are up. The S&P 500 gives you an adjusted average of all the stocks in the index. And by definition that means there will be stocks that do better than the S&P 500 index, and stocks that do worse.

And some stocks may not only do worse than the S&P 500, but much worse.

In this case, your hunch is right. The stocks in the chart at left are components of the S&P 500 index that have declined in value since March 9.

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. Follow Matt on Twitter at: twitter.com/mattkrantz