This year’s selloff in China’s stocks and currency is reviving painful memories of the country’s last market rout, in the summer of 2015. If anything, things look more worrying this time around. Shares in Shanghai are the world’s worst performing among major markets this year, tumbling 17%. The yuan has slumped 3.6% against the dollar since the start of June, pushed down by a combination of selling by nervous investors and the Chinese central bank’s efforts to guide the currency lower as a trade conflict with the U.S. escalates. On paper, even those big market moves pale in comparison with 2015. Three years ago the Shanghai Composite Index lost nearly half its value in the two months starting in June, bottoming out only in early 2016: They have never since regained their mid-2015 highs. The central bank also shocked markets with an abrupt 2% devaluation of the yuan […]