Early September 2001: Sharp Increase in Short Selling of American and United Airlines Stocks

There is a sharp increase in the short selling of American and United Airlines stocks on the New York Stock Exchange prior to 9/11. A short sell is a bet that a particular stock will drop. Short selling increases 40 percent over the previous month for these two airlines, compared to an 11 percent increase for other big airlines and one percent for the exchange overall. United’s stock will drops 43 percent and American 39 percent the first day the market reopens after the attack. [Reuters, 9/20/2001; San Francisco Chronicle, 9/22/2001] There is also a short spike in the short interest in Dutch airline KLM three to seven days before 9/11, reaching historically unprecedented levels. [USA Today, 9/26/2001]