Earlier this week I received an email questioning my percent decline and gain numbers for the current market.

"How can the S&P 500 still be down over 45% if we've had a rally of more than 25%?"

Experienced investors understand the concept that a 50% loss requires a 100% gain to break even. But a chart gives us a clear illustration of the exponential relationship between a percent loss and the gain required for a full recovery.

Fortunately, the right end of this "Hockey Stick Curve" is rarely relevant for broad indexes. But individual stocks are a different matter. As of today, Citigroup, Inc. (C) has rallied 319% off its low of 1.02 set on March 5th, which was a 98% decline from its all-time high in December 2006. But even with its 319% gain, the stock is still down 93.6%.