The blue chips plunged more than 200 points after Standard & Poor's downgrade of American debt and ongoing euro zone debt worries rocked traders' confidence. Meanwhile, safe-haven assets rallied: gold leaped past the $1,700-mark and 10-year Treasury prices climbed. As of 9:32am ET, the Dow Jones Industrial Average slid 226 points, or 2 percent, to 11,218, the S&P 500 tumbled 24.1 points, or 2.1 percent, to 1,174 and the Nasdaq Composite dipped 82.5 points, or 3.3 percent, to 2,451. Volatility is expected to be high on Monday. In fact, the New York Stock Exchange invoked "Rule 48," which enables market makers to hold off on sending initial price indications at market open in a bid to help markets open smoothly. For the first time in history, S&P cut America's top-notch credit rating one notch to AA-plus from AAA after the close of trading on Friday. The ratings company also said it may slice the ratings another notch over the next two years. S&P's move came as a result of concerns over the country's substantial public debt burden and deep divides within Congress that almost sparked an unprecedented default on US sovereign debt.