The story is becoming more and more complicated..

Link to Wired.com:
http://blog.wired.com/27bstroke6/2008/09/six-year-old-st.html

I would blame the guy from the research firm that ended up posting the news on Bloomberg's news site which then got sent out as a news alert and started the large sell-off of United stock.

http://www.nytimes.com/2008/09/09/business/09air.html?_r=1&oref=slogin

What would happen if one of those sites were hacked with a fake press release from some major company. It could affect any companies stock if people believed it to be true.

Here's a new story (Thursday) from the Wall Street Journal

"Single Web Hit Led to UAL Glitch, Tribune Says"
http://online.wsj.com/article/SB122109238502221651.html?mod=yahoo_hs&ru=yahoo