Dow down 416 pts! - Why?

Two reasons why the stock market crashed yesterday, was 1st, the recent drop of the chinese stock market of 9% overnight, damaged the global economy. Also the 2nd reason is we've never had a dramatic loss since 9-11. Therefore the economy's been growing and not decreasing, and inorder to keep everything balanced the stocks must decrease maybe even by 416 points to get us back on track.