Emerging-market equities, one of the top-performing segments of the global economy in 2017, have undergone a dramatic reversal thus far this year, tumbling amid the twin headwinds of a stronger U.S. dollar and ongoing trade uncertainty between the U.S. and China. The region has been among the hardest hit by trade headwinds, particularly this week, after President Donald Trump threatened tariffs on some $450 billion more in Chinese products. The Trump administration dialed up the rhetoric late Tuesday, accusing China of waging a systematic campaign of “economic aggression” in a report released Tuesday.via