MIAMI — United Airlines and its stockholders experienced the potential risks inherent in a high-tech society Monday when outdated information about a 2002 bankruptcy filing zoomed around the Internet and prompted a run on the company's stock.

For a short time Monday, United stock fell 75 percent, before mostly rebounding. The company said the sell-off began after a Chicago Tribune article from six years ago about UAL's bankruptcy filing was found on the Broward-based South Florida Sun Sentinel Web site with the date changed to Monday. It was then republished by others.

It's unknown how much money may have been lost or made because of the article. The airline said it has demanded a retraction from the Sun Sentinel.

"This is a serious event that resulted in the halting of the trading of our stock today," United spokeswoman Jean Medina said Monday. "It is what happens when people are irresponsible and don't check facts, and our lawyers are investigating."

In a statement Monday, the Tribune Co., the Sun Sentinel's parent, said the article was picked up by an investment advisory and research firm and republished as if it were current.

"The story was located in the archive section of the Web site of the Sun Sentinel in South Florida," the statement said. "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."

VULNERABILITY TO RUMOR

Richard Lehmann, president of Income Securities Advisors, a Miami Lakes-based publisher of financial information, said his company posted the article to the Bloomberg financial news service after finding it on the Sun Sentinel site.

Lehmann said a reporter, looking for distressed company news to post on Bloomberg, did a Google search Monday morning under the term "bankruptcy 2008" and the United bankruptcy story came up as the top story, dated Monday, with a link to the Sun Sentinel.

"Our reporter took it for what it said, put a story together, put a link (to the Sun Sentinel) and submitted it and put it on Bloomberg," he said.

That story went online at 10:55 a.m., he said.

"The minute the story came up, the phone started ringing around here, and that's when I became aware of it, and I knew something wasn't right," Lehmann said. "I checked all the stories under Bloomberg and we were the only ones reporting this and we don't originate news stories, so something had to be wrong, and I asked Bloomberg to pull it."

At 10:56 a.m. the stock was trading at $11.51, then plunged to $3. Shares resumed trading at 11:01 a.m., and recovered most of the loss by 12:29 p.m., when the stock was at $11.30, according to Bloomberg.

Bloomberg yanked the story at 11:08 a.m., but the stock had already plummeted.

"It seems to be the effect of computerized trading — when a price moves, a lot of sell orders get triggered automatically," Lehman said. "It's one of the vulnerabilities of our system. Unfortunately it lends itself to someone doing this on purpose, which is probably going to get looked into."

THEORY OF LIABILITY

Roy Peter Clark, senior scholar at the Poynter Institute, a journalism school in St. Petersburg, chalked Monday's phenomenon up to the lighting-fast speed at which information can travel.

"In this time of Internet technology and viral media, rumors, as we know, are not only proliferated but they travel at the speed of light ... and the consequences of passing along, let's call it a mistake or a malicious rumor, can be devastating," he said.

Jim Corridore, an airlines and air freight analyst at Standard & Poor's Equity Research, said he expects a regulatory review of the events, "as well as shareholder litigation."

Attorneys already may be "trying to frame a theory of liability," said Miami securities attorney Thomas Tew, a partner in Tew Cardenas. Lawyers at a minimum would have to show gross negligence, he said.

"Certainly, lawyers will be crafting a theory, and it won't be long before ... (a lawsuit) will emerge for those people who sold in a declining market and then the stock recovered," Tew said.

United exited bankruptcy in February 2006, and along with the industry has struggled to cope with high fuel costs this year, posting a $2.7 billion loss for the second quarter. The airline is cutting back its domestic capacity by 14 percent in the fourth quarter, and has just pulled out of the Fort Lauderdale-Hollywood and Palm Beach international airports.

"United continues to execute its previously announced business plan to successfully navigate through an environment marked by volatile fuel prices and continues to have strong liquidity," the airline said in a statement Monday.

BLOOMBERG FACTOR

United stock had closed at $12.30 on Friday, and opened Monday at $12.17. It fell to as low as $3 Monday morning before trading was halted. Trading resumed after United issued a statement saying the report of its bankruptcy was untrue. The stock closed at $10.92 on Monday, down 11 percent. Other major airline stocks fell Monday as well.

In a story on its own Web site Monday, the Chicago Tribune said the article did not have any discernible effect on United shares until after 10:53 a.m., when it was posted to Bloomberg.

Joe Schwerdt, deputy managing editor-interactive for the Sun Sentinel, told the Chicago Tribune that internal tracking records show that no one at the paper had opened the original story file since 2003. The story would have been available via a search on the site, but no one outside the paper should have had access to the story file, Schwerdt said.

In a staff story on the Sun Sentinel's Web site Monday afternoon, the Sun Sentinel referred to the 2002 article as a "link to an archived www.SunSentinel.com story."

Earlier Monday, the Chicago Tribune issued a statement saying it had been "informed that a 2002 Chicago Tribune news report about United Airlines' financial condition was picked up and circulated on the Internet Monday morning. The story is not current. We are looking into the situation."

Poynter's Clark said he believes what happened to United will happen again because of newspapers' emphasis on speed in the Internet age.

"In the old days, which are not so long ago, the news cycle gave you a little time to check things out," he said. "There is now an even greater incentive to get things up on your Web site as soon as possible to drive traffic there."