U.S. stocks have reached a critical line in the sand. Why the next move could be a 10% drop.

U.S. stocks were flirting with a critical threshold on Wednesday that, if broken, could portend another 10% drop for the S&P 500, according to one technical analyst.

​U.S. stocks were flirting with a critical threshold on Wednesday that, if broken, could portend another 10% drop for the S&P 500, according to one technical analyst.