Add trade tensions and the threat they pose to economic growth to the list of worries that were already dogging stock-market investors in 2018. President Donald Trump’s announcement Thursday that he was set to impose tariffs on aluminum and steel imports sent stocks tumbling. Implied volatility, as measured by the Cboe Volatility Index VIX, +10.19% or VIX, jumped Thursday afternoon, ending the day around 13% higher at 22.47, and rose Friday to trade above 25. The announcement drew angry responses from global leaders, while Trump tweeted that “trade wars are good, and easy to win.” “For now, the more predictable ... (full story)