@nytimes: The tit for tat over President Trump’s tariffs has caused volatility in the stock market and panic on trading desks across Wall Street. Our markets reporter walks us through the president’s first 100 days by looking at the S&P 500, a benchmark for the U.S. stock market. Video by Joe Rennison, Christina Shaman, David Jouppi and Gabriel Blanco/The New York Times. #Stocks #DonaldTrump