Moon cycles have been shown in academic research to be predictive. Recent price history of S&P 500 shows clear moon cycles with a bottom around the full moon. The moon cycle is also related to the intermediate cycle in Welles Wilder's delta methodology.
Elliott Wave theory would predict we are in correction wave. After eight years of a higher index the correction should be large. The decline labeled 1 is not sufficient. That means that the large and swift 3rd wave decline is coming. The current wave 2 might be over (a perfect 61% retracement) or it might linger a bit longer at this level. It is likely that the 3rd wave down will coincide with a growing moon.