I came across this article discussing how the VIX Flip Indicator tracks the fear of investors. It seems to be an interesting tool, which I would like to investigate. The calculation of this indicator is not communicated in the article. Can you refer me toward its calculation? No good results from Google.
This indicator seems to be similar to William's Vix Fix which is also known as Synthetic Vix.
On plotting the values of Vix Fix, the monthly chart of the S&P 500 looks similar to the chart given in the link shared by you.
Formula: VIX Fix = (Highest (Close,22) – Low) / (Highest (Close,22)) * 100
It seems that you can only get access to it through paying the people that came up with it.
I, for one, am not buying it and not linking to them either. I recommend you do the same.