Stocks are showing the kind of volatility that preceded major falls in the past, suggesting to some that one of the most blistering U.S. rallies on record may be nearing its end. The market is undergoing big swings under the influence of plunging oil prices and resulting turmoil in Russia, as well as the Federal Reserve's only gradual shift away from ultra-low interest rates and - on Tuesday - data showing a sharp acceleration of the U.S. economy. The series of short-term rallies and selloffs has revived memories of events before the "Black Monday" crash of October, 1987, and more recently the global crisis of the ... (full story)