According to a survey by Bank of America Merrill Lynch global fund managers are most worried over headwinds from China.

Big challenges in China:

According to global investors Chinese economy is likely to slow down further and world's second largest economy might even hit recession.

Hot money (portfolio inflows) is flowing away sharply from China. Estimates vary but all of them is quite large. According to estimates about $400-$600 billion this year has flown out of China.

Chinese reserve is quite large, but domestic debt even larger.

Chinese authorities struggling to stabilize country's stock market, which is down by -6.15% today.

According to the survey 2 out of 3 investors consider either China or emerging market debt as biggest tail risk.

About 10% investors are concerned over inflation and FED falling behind the curve.

In July every 1 in4 investors were worried about Greece, in August it fell to below 5%.