That’s the result of mechanically applying the Gravity dates since January 2008.

But I can hear the skeptics say: “Wait a minute, you are pulling a fast one, 'a la Taylor' here. You can’t expect to always nail the top/bottom of the move.”
To which I reply: “Perfectly correct. So, let’s take a look of what happens if we apply the same mechanical system to buying the open/close.”

Then the result would be 401 points gained by buying at the open v. 461 points gained from buying at the close of the Gravity dates. Not too bad, considering that a buy and hold strategy would have lost 43 SPX points during the same period.
And that’s without even looking at the SPX barometer (the extreme swing readings marked above/below the high/low of the daily bar) or the support/resistance levels provided for in the numerous accompanying charts.