STR/AFP/Getty Images A textile worker sews at a factory in Huaxian County, in China's northern Henan Province.U.S. stock futures pointed to a sharp drop at the open on Wednesday, with traders heading for the exit after the Trump administration said it will slap tariffs on a further $200 billion in Chinese goods. What are markets doing? Futures for the Dow Jones Industrial Average YMU8, -0.83% slumped 234 points, or 0.9%, to 24,694, while those for the S&P 500 index ESU8, -0.69% dropped 23.20 points, or 0.8%, to 2,773.50. Futures for the Nasdaq-100 indexNQU8, -0.86% fell 70.50 points, or 1%, to 7,230.75. The potential for a selloff comes after the Dow DJIA, +0.58% scored its longest winning run in a month on Tuesday, ending up 0.6%. The S&P 500 ESU8, -0.69% closed 0.4% higher, while the Nasdaq Composite Index COMP, +0.04% finished up less than 0.1%.via