By Stan Choe and Alex VeigaThe Associated PressNEW YORK — The escalating coronavirus emergency sent the stock market Thursday into its worst slide since the Black Monday crash of 1987, extending a sell-off that has now wiped out most of Wall Street’s big gains since President Donald Trump took office. The S&P 500 plummeted 9.5%, for a total drop of 26.7% from its all-time high, set just last month.Read more on NewsOK.com