As a matter of fact the House and Senate are also exempt from similar laws where they can enrich themselves and its totally legal. They don't like to talk about it of course but if you recall 60 minutes did a story on this a few years ago.
Pelosi defends record after "60 Minutes" report - CBS News
Former Speaker of the House Nancy Pelosi defended her record on credit card reform after a "60 Minutes" reportraised questions about lawmakers potentially executing financial transactions based on insider information.
There is no law prohibiting members of Congress from using non-public information to form their own investment strategies, but the "60 Minutes" questioned several lawmakers about transactions that may have had at least the appearance of a conflict of interest.
Congress trading stock on inside information?
Questioning Pelosi: Steve Kroft heads to D.C.
One of them was Rep. Pelosi, who participated in a 2008 IPO from Visa, just as legislation that would have hurt the credit card companies began moving through the House. Pelosi bought 5,000 shares of Visa at $44 and the stock price rose to $64 just two days later. The credit card legislation never made it to the House floor.