Dow down 416 pts! - Why?

The stock market took a dramatic blow a few days ago. One of the more primary reasons for this is because of the even more dramatic 9% drop in China's economy, which in the long run affected the global economy, therefore affecting us. Another reason, is that the stock market hasn't had an extreme drop like this since the time of the World Trade Center attacks. After doing good for five straight years, with little drop, it is only natural that the stock would cave in a bit sooner or later, it's just unfortunate that it had to be combined with the global economy drop from China.