The Wall Street Journals runs a story on how the Google News algorithm mis-read an old story (from 2002) about UAL's financial problems as a breaking news, posted it, thus triggering other algorithms which sell stocks based on news stories.
Google traces the appearance of the 2002 article in its search engine to a process that began late last Saturday night. At 10:36 p.m. PDT, Google's "crawler" -- the technology that finds Web pages -- discovered a new link on the Web site of Tribune's South Florida Sun-Sentinel newspaper in a section called "Popular Stories: Business." The article -- which didn't carry a date but was published by the Chicago Tribune in December 2002 -- hadn't appeared there when Google's crawler last visited the page at 10:17 p.m., the company said.
From the Sun-Sentinel site, the article became available through Google News service, accessible if a user searched for keywords like "United Airlines." The article didn't appear in any of the headlines on Google News's home page, but it was picked up and sent via email to people who had created a custom Google News alert about UAL or related topics.The stock market opened Monday with no drop in UAL shares, but the UAL story began circulating widely via a posting by research firm Income Securities Advisors Inc. that was made available to users of Bloomberg L.P., the financial-news service widely watched on Wall Street. Shortly after a headline from the outdated report flashed across Bloomberg screens at about 10:45 a.m., UAL shares began a precipitous drop. Over the next 15 minutes, before Nasdaq halted trading, they dropped as low as $3.
It's not the first time erroneous news reports have swung stock prices, but the increasing reliance on Google, Yahoo and other news aggregators ratchets up the speed with which information -- correct or incorrect -- can spread across the globe.