Yesterday's dramatic "rotational" divergence between tech stocks and the rest of the market, which as Sentiment Trader pointed out the only time in history when the Dow Jones closed at a new all time high while the Nasdaq dropped 2% was on April 14, 1999, stunned many and prompted Bloomberg to write that "a crack has finally formed in the foundation of the U.S. bull market. Now investors must decide if any structural damage has been done."

This year's hottest stocks, companies from Facebook Inc. and Apple Inc. to Netflix Inc. and Nvidia Corp., buckled Friday, spurring losses that sent the Nasdaq 100 to its biggest drop relative to the Dow Jones Industrial Average since 2008. 

An alternative explanation is that the purge in tech stocks, responsible for half the market's gains in 2017...