Thomas:

If I am right, then typical behavior is to drive SP up so as to suck in additonal longs. Then a move down with increasing ferocity. Then late morning, here is a halt in rate of decline and even a move back up. Theb in the afternoon, the attack resumes spiralling lower in SP. If it is a one day event (which it usually is) then descent slows and reverses late afternoon. One time about three years ago, I saw the sell off continue into day 2 with a recovery mid morning.

As this is a Friday, if it happens today, I would expect a one day event. The "boys" would not want an exogenous event occuring over the weekend which would wreck their plans. But, with 13 million outstanding shorts it has to be coming at some point. Either that, or you will see the greatest short covering rally in history. And I doubt that!