When the smart money heads for the exit, it's time to take notice. That's the message from Goldman Sachs' decision to sell down its share in Industrial & Commercial Bank of China.

Sales by keystone foreign investors are a sign of the times for China's banks. Goldman's decision to reduce its stake in ICBC to 2.4% from 2.9% comes after a move by Bank of America Merrill Lynch in August to sell about half its 10% stake in China Construction Bank.