It’s a little old by now, but this is an interesting story about how automated news crawling wiped $300m off United Airlines’ market cap. Basically this is what happened:

• Back in 2002 United Airlines was on the brink of bankruptcy – that obviously made the news
• For some reason an old story became popular on the South Florida Sun-Sentinel newspaper website – it got put back onto the front page but without a date
• Because there was no date the Google News crawler picked up the story and put it onto today’s news
• Several other news aggregators picked up the story and it “eventually headlined as a news flash on Bloomberg”
• That triggered automated trading programs to sell-sell-sell
• The selling spree wiped 1.14 billions dollars off of United’s market cap
• During the day stock recovered but ended $300 million down

Crazy stuff.