No, it's just "actively managed" by (among others), Treasury Secretary Hank Paulson, a.k.a. Chairman of the Plunge Protection Team. http://biz.yahoo.com/seekingalpha/070812/44214_id.html?.v=1 lol Wow.
If there is a PPT, they are traders just like us, albeit with deeper pockets. And like us, if they countertrend trade, they must eventually unwind a bad position. Or face a margin call. History is replete with examples where Governments intervened in markets for political purposes, ultimately to the deep regret of the citizenry. Think of the innumerable failures of fiat currencies. Or attempting to maintain a fixed precious metals standard in the face of inflation. Margin calls don't always come from brokers. Sometimes they come from the outside world.
No, the Plunge Protection Team is the government. Read the article all the way through. I think you'll be surprised.