Airline share price plummets after website links to old news story

But the story dated from 2002, when the airline did declare itself bankrupt, a state from which it has since emerged. The Chicago Tribune story had a circuitous route to infamy via the website of  sister newspaper the South Florida Sun-Sentinel, Google News and Bloomberg's financial news service, where it reached stock trading floors.

As soon as traders saw the headline in Bloomberg the sell-off began and United shares dived from a day-opening price of $12.17 to $3 as 15 million shares changed hands.

Google says that the story appeared on the Sun-Sentinel website on Saturday evening and was indexed by its Google News system. The story itself was undated but the link had newly appeared on the list of most popular business stories, so was indexed by the Google News system.

"The article was indexed and then available through Google News search, but was not shown on our headlines pages," said a statement by Josh Cohen, business product manager for Google News.

That story then appeared in a Google News search for bankruptcy-related stories performed by a reporter at Miami-based investment service Income Securities Advisors. It is one of a number of third party content providers to the proprietary Bloomberg news service, which typically appears on dedicated terminals on trading floors.

When the story appeared in the Bloomberg service the sell-off began. Within five minutes Bloomberg was carrying another story reporting a 33% drop in United's share price. Within 25 minutes it carried a story on United's denial that it was going bankrupt.

Tribune, the owner of the Chicago Tribune and the South Florida Sun-Sentinel, said that while the article had not been reposted a link to it had appeared anew on the 'most viewed' section of the Sun-Sentinel site. It said, though, that someone in the chain of publishing events should have noticed that it was an old story.

"[The] story contains information that would clearly lead a reader to the conclusion that it was related to events in 2002. In addition, the comments posted along with the story are dated 2002. It appears that no one who passed this story along actually bothered to read the story itself," said a Tribune statement.

"Because the Sun-Sentinel included a link to the story in its 'Popular Stories' section, and provided a date on the article page of September 7, 2008, the Google News algorithm indexed it as a new story," said Google's Cohen. "We removed this story as soon as we were notified that it was posted in error."

United's share price recovered to $10.27 by the close of trading that day.