Yes, the Dow dropped 7.87% today. The Nasdaq tanked 8.47%. And the S&P 500, down 9.03%, had its worst day since Black Monday. Monday's gains? Virtually gone.

Economic fears were renewed today by more concerns about the credit markets, the Fed's ugly Beige Book news, and by disappointing retail sales. Some of the usual suspects in the financial sector dropped -- Morgan Stanley (NYSE:MS), Bank of America (NYSE:BAC), and Citigroup (NYSE:C), for instance, each lost more than 10% today.

But the net was cast wider yet: Concerns about energy demand dinged ExxonMobil (NYSE:XOM) and Chevron (NYSE:CVX) 14% and 13%, respectively, while consumer-spending concerns weighed on Jones Apparel (NYSE:JNY) and Macy's (NYSE:M).

Fools, we know it's tough to be patient and remember temperament at times like these. It's easy to get caught up in the whipsawing up-and-down volatility, the likes of which many of us have never seen.

As individual investors, we feel the same pain you do, watching the market day in and day out. We've lost money, just like you have. We've seen our 401(k)s shrink to mere ghosts of their former selves. We get it. It's a rough time out there to be an investor -- working hard to choose quality companies, investing in them for the long haul, and hoping to see that good work pay off one day with retirement, or your child's Ivy League education, or that second home on a hideaway beach somewhere.

But please, remain calm. Remember the long-term philosophy we've embraced together here at The Motley Fool over our 15-year history. Think about the incredible opportunities this market mayhem is presenting us with. There are companies trading at such cheap levels here that we'll be kicking ourselves years from now if we turn away from the market at this time.

Take a deep breath, don't push that "sell" button, and stay tuned to for ongoing analysis and commentary.

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Online managing editor LouAnn DiCosmo and advocacy editor Brian Richards do not own shares of any company mentioned here. Bank of America is a Motley Fool Income Investor pick. The Fool's disclosure policy prefers Mary-Kate over Ashley.