On April the 24 th , the Wall Street Journal ran a story detailing the huge move of the VIX index in the opening 30 minutes of trading on the previous Wednesday. The VIX spiked up 12% in 30 minutes despite the underlying S&P 500 index not moving much at all. To put this 12% move into perspective, the current expected move in a 30-minute period is less than 2%. In addition to being a large move, the timing was suspicious. It was during this period that the settlement price for the April VIX futures was calculated. Anyone holding a long futures position would have benefitted greatly, at the expense of the shorts. There have been rumors about the manipulation of the VIX index for many years. Whether or not the anomalously large S&P 500 option trades during the settlement period are evidence of manipulation, part of an arbitrage or just coincidence, the fact is that the VIX settlement period is often atypically volatile. This is alarming for market-makers and professional a
To be able to trade volatility we need to understand it, particularly the interplay between clustering and mean reversion. Most of the predictability of volatility is due to one of these two features.