Unusual Trading in Stock Options Prior to 9/11: Government Destroyed Documents Regarding Pre-9/11 Put Options http://globalresearch.ca/index.php?context=va&aid=19750

'Sources tell CBS News that the afternoon before the attack, alarm bells were sounding over unusual trading in the U.S. stock options market. An extraordinary number of trades were betting that American Airlines stock price would fall.

The trades are called "puts" and they involved at least 450,000 shares of American. But what raised the red flag is more than 80 percent of the orders were "puts", far outnumbering "call" options, those betting the stock would rise. Sources say they have never seen that kind of imbalance before, reports CBS News Correspondent Sharyl Attkisson. Normally the numbers are fairly even.'