This is from a 2002 article I believe but interesting historical perspective. Since the vix was devised in 1993, and revised in 2003, I believe the numbers were reverse enginered from the original vix on the oex and not the spx. Interesting to note as well the dow was up 250% in the 5 years proceeding this event. "While the level of 50 marks a normal VIX extreme in recent years, a contrarian speculation buy signal, there was one stunning event in history where the VIX actually exploded to almost unthinkable heights. On October 19th, 1987 the VIX rocketed up to close at the breathtaking level of 150! Merely one trading day earlier it had closed at 36, a normal level. Over the next five trading days, the VIX closed above the staggering level of 100 three more times. From October 19th to October 30th the VIX closed above 60 for the entire ten trading-day stretch, an unprecedented development never seen before or since. On a long-term VIX chart, this huge anomaly sticks out like a central banker at a rap concert. This mega-VIX spike was an incredible event that will go down forever in the annals of market legend."