The Economist called it ”a snort from a dragon’s nostrils.” At the end of February as China’s stock market index fell by more than 8% stock markets tumbled around the globe in their steepest decline since the attacks on September 11 2001. Adding to the anxiety were concerns about a possible shakeout in the U.S. sub-prime mortgage market and former chairman of the Federal Reserve Alan Greenspan’s comment that the U.S. economy could face a recession. Since then markets have recovered only to drop again and then climb once more. What is causing this volatility and what does it mean for investors? Knowledge at Wharton asked for comments from Wharton finance professor Jeremy Siegel whom we spoke with first and Wharton management professor Marshall Meyer who closely follows China’s economy.