On Aug 15 & Aug 16 pre-market, the VIX spot index was mostly around 12 and below 12. But just before market open the VIX spot index shot up. The final settlement price hit 12.95, of which the spot index has never reached that level. Does anyone have any idea what happened to the VIX? Is that purely final settlement price manipulation? It seems to be a surprise that people can move the final settlement price by almost 1 volatility point.