Manipulation in the VIX?
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2972979 [papers.ssrn.com]
2017-05-25 07:34
At the settlement time of the VIX Volatility Index, volume spikes on S&P 500 Index (SPX) options, but only in out-of-the-money options that are used to calculate the VIX, and more so for options with a higher and discontinuous influence on VIX.
source: ML