This week United Airlines’ stock (UAL) fell to a quarter of it’s price within minutes, from $12.50 to $3, after a 2002 article about the company’s bankruptcy circulated the internet as fresh news. The SEC is currently investigating the matter, but here are some interesting details about what happened :

Sometime between 1:00 a.m. and 1:36 a.m. EDT on Sunday, September 7, 2008, a link to this old article appeared under the “Popular Stories Business: Most Viewed” section of the Sun Sentinel’s site’s business section. This section is dynamically updated based on the traffic volume of stories being viewed. The Wall Street Journal reports that this old story resurfaced when a “single late-night” visitor viewed the story on the site during a “low-traffic period.”

At 1:36 a.m. EDT, the Google crawler discovered the new link on the Sun Sentinel site and noted that the link was not there previously when the Googlebot had last crawled the site 19 minutes earlier. The crawler interpreted this as a new link and followed the link to the story. The Tribune states that “no new story was published and the old story was not re-published — a link to the old story was merely provided.” Unfortunately, there was no date on the story itself, so the Googlebot used the only date it could find on the page as the context for the article, which was the actual date, September 7, 2008, as it appeared in the header of the page for the Sun Sentinel site (see the image to the left). Google states that “the article was indexed and then available through Google News search, but was not shown on our headlines pages.”

Read on for more details: http://www.hothardware.com/News/Internet-Bots-Anatomy-of-a-Stock-Selling-Frenzy/