The biggest players seem to be selling shares in businesses that rely on US consumer spending. There's not a lot of confidence in the US economy right now. Does anybody know if legislation was ever passed to ensure that a repeat of 2008 wouldn't happen again? If not then I'd say that it could easily happen again. This volatility may be a sign of history repeating itself.
Disclaimer: I'm a real estate guy, not a stock guy. I'm also Australian so there's a good chance I don't know what the fuck I'm on about.