From The Wall Street Journal: How trade is trashing stock markets

The S&P 500 is down about 6% over the last month, and other indices have largely followed suit. In fact, the stock market sell-off has hit virtually every market in the world. At the same time, volatility has been skyrocketing. Most of the uncertainty and selling has been driven by anxiety about trade. U.S. President Donald Trump has been threatening massive tariffs on multiple products and America's biggest trade partners, including the European Union and China, have announced their planned retaliation. Many worry that trade tensions risk ending the synchronised global growth upswing before it starts and depressing the potential for stocks to deliver on their high valuations. It's a tense time for investors.