A week prior to the stock market crash of 2008/2009, US Congressmen were advised to sell their stocks as a crash was imminent. This is not unusual. Congressmen are privy to insider trading. Many of them get regular briefings from brokerage houses, the FED, and the Treasury.

A few days leading up to the 9/11 attacks, hundreds of put orders or shorts (betting that the stock will drop in value) were placed on American Airlines and United Airlines. Highly unusual and heavy volume--obviously a group of people had insider information.

SEC quickly investigated and stated that these investors "clearly did not have ties to terrorists." Who would be above that kind of suspicion? A trader, no. CIA, FBI and defense officials, maybe, but would still be investigated. US Congressmen, yeah.

Furthermore, the SEC destroyed all the evidence/documents related to this case. Who has the leverage to make the SEC do that? No one will ever know who placed those short orders.

It explains why Congressmen didn't demand on public television an investigation on these put orders. Its also possible that these put orders were used to black mail US Congressmen from not challenging the circumstance of the events on 9/11.

Now, I'm not saying that Congressmen knew of the 9/11 attacks. I'm saying that they simply acted on a stock tip. And covered it up when it backfired.