What US and Chinese stocks have in common

Plunging oil prices and China's market meltdown have been cited as two big culprits behind market volatility this summer, but history shows less correlation between these markets and U.S. stocks than many investors might expect. In the case of Shanghai stocks, the S&P 500 (INDEX: .SPX) has been very loosely correlated, but in the last several sessions the two have moved slightly closer ...