There was a bizarre moment this afternoon, when in the 40 minutes heading into the final hour of trading, the VIX kept rising and rising, preventing the S&P from doing its sworn duty of spiking higher into the weekend. And then, just after 310pm ET (or 1210 PT), the VIX collapsed, plunging by as much as 14 vols from 54.39 - the highest print since Lehman - to 40.84, the low for the day, and unleashing another unprecedented stock buying cascade, which almost sent the Dow green. 

What happened?