Because Twitter is a fucking retarded way to gather information.

Thanks CNN, for making it fashionable, and thanks all other media, for always shamelessly copying the AP instead of doing your own damn legwork. Hard to corroborate stories when they all use either the AP or Reuters.

Personally, I thought it was funny as hell, proving that IT security at the AP a POS (the cause was a "well-crafted" phishing email), and Twitter is aptly named.

The market goes crazy all the time. Blame micro-second transactions causing invariable cascades just like this. It's all automated. Don't you remember that "rogue algorithm" that caused the market to tank several months ago?