If you notice the first huge day up was on Wednesday, 12/26/2018 or 5 days after triple witching Friday on 12/21/2018.
Next, if you count exactly 12 weeks from the first huge move up on the right side of the "V" you come to Wednesday, 3/20/2019...the day the large downward move and "W" will begin.
S&P 500 Close On 3/15/2019 |