WTF Just Happened to the Bond Market and Credit Spreads?

Credit spreads have exploded in recent weeks, and not just the triple hooks. It has spread to other parts of the public market. And now that September has finished up, we might finally get more fundamental trading in USTs. Part (much?) of the recent selloff has been, well, three September effects. I'll explain what those are/were and what that might mean. It did for Oct 1.