> In September an average of 1,581 shares a day of eis were sold short, representing 17% of the daily total trading volume. On October 2nd, five days before the attacks, a whopping 227,820 shares were shorted

It’s misleading to compare an average with an extreme, especially since October 2nd is the first Monday of the month and the fourth quarter (probably books being balanced). It would be better to compare with the maximum in the whole of September or July.