China’s long history of tempestuous trading spilled over its borders this year, signaling that a once-isolated market is moving to the center of global finance. Chinese volatility upended markets from Tokyo to London , and helped send some emerging-market currencies to their weakest levels in nearly two decades. Commodities including copper and aluminum plumbed six-year lows as China, one of the world’s biggest metals consumers, reined in buying . While a summer stock crash and the surprise devaluation of China’s yuan spooked investors world-wide, the repercussions also exposed the growing pains of a maturing financial market. With one trading day left in 2015, Shanghai’s stock market is still up 10.5% this year, despite losing more than 40% of its value over the summer. That gain outpaces the 1% rise in the S&P 500 through Tuesday, and the 9.6% advance in Germany’s DAX and 7.35% gain in the Stoxx Europe […]