Bears Finally Taking Charge?

The U.S. stock market sold off quite heavily today, with the S&P 500 dropping 3%. Since its January 19 peak, it is down 7.5%. Is this the beginning of a major sell-off?

I'm not sure, I've given up on short term market timing. But it does seem more likely than not. And more importantly, given the elevated valuation levels and the high probability of a double dip recession, it seems clear that stock prices should fall on fundamental grounds.