(AP)  Stocks went on a wild ride Thursday as investors struggle to gauge the impact of the coronavirus outbreak on the global economy. The Dow Jones Industrial Average dropped 960 points in morning trading, erased much of the loss by midday before giving way to another round of selling in the afternoon. The bond market saw similar volatility, with the yield on the 10-year Treasury at one falling to another all-time low. More companies including Microsoft are warning their results will be hurt. The furious selling of the past week has brought the S&P 500 10% below the record high it set just a week ago.