Selling followed sharp overseas stocks declines and was broad, with all 10 major S&P 500 sectors losing ground. The Dow and S&P 500 both snapped two weeks of gains. For the week, the Dow was down 1.3 percent, the S&P 500 down 1 percent and the Nasdaq down 1.3 percent. China’s securities regulator warned investors to be cautious as Chinese shares hit seven-year highs.