In one chart: The VIX says the stock-market low may be in

The Cboe Volatility Index is a guide to human nature, says a prominent Wall Street bull. Canaccord Genuity analyst Tony Dwyer has characterized the stock market?s early February plunge as a phenomenon known as a ?shock drop,? in which a correction is sharp enough to cause the 10-week rate of change in the Cboe Volatility Index (^VIX), or VIX, to spike to 125. The rate of change, or ROC, measures the percent change in price from one period to the next.