"Black Monday" causes a slide at the stock exchange

I'm not the only one looking at the recent volatility of the Shanghai Stock Exchange with more than normal interest. Up to not so long ago China's relative isolated financial markets caused movements at the stock exchange that often went directly opposite the global sentiments. Also, a drop in exports - a drop that has not yet taken place - could at least partly be compensated by domestic demand, was an argument I supported.
Now, one of the suggestions is that today's drop of over 5 percent was at least partly caused by the problems in the US-markets and the exposure of Chinese banks to the mortgage crisis and its fallout in the US, especially hitting China's financial institutions.
This switch is going a little bit too fast for me. While for this kind of financial markets sentiments are often more important than facts, I'm not that sure the sentiment has made that switch.

Update: The China Daily comes with another explanation that makes more sense in the Chinese context. It signalled panic selling after Ping An, China's second largest insurer, announced plans to soak up 180 billion Rmb (€ 18 billion euro) with an additional share and bond offer. That is considered to be a bit too much, even for the enthusiastic Shanghai market. That now seems a crisis that is easier to contain than other crises stories.