Daily chart SPX Stoch RSI has been very regular.

A simple sine wave overlay on the S&P Stochastic RSI has been timed almost perfectly for a year and a half.
The period is about a month long.
Notice the "short circuit" between peaks during November 2014 and October 2915.
First half of each month has been bearish; second half of each month has been bullish.
Sine Wave

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