Market changes rarely have one cause. The NSA story hit in June. While I think Zero Hedge is the repository of much bad investment advice, they have a very interesting chart from June.
http://www.zerohedge.com/... Quite frankly I don't care who that mystery buyer is, though I expect that its the Fed fulfilling its role as a central bank. What I want to point out here is that, for the first month that the NSA stuff was around and the last month we have data for, international buyers dumped US Treasury bonds.
Lets be clear, a lot of this selling is about the possibility that interest rates will rise in the US. On the other hand it seems like foreign investors might be getting tired of lending the US money that will be used to spy on them. If NSA actions cause interest rates to spike it will make the damage the tech industry is taking look like a walk in the park.
Once again, the national security apparatus seems incapable of predicting or appreciating the consequences of its actions. The national security state continues to prove itself the largest threat to national security that we now face.