Just a guesstimate when considering last two meltdown. Each was steeper than the last, and each plunged further in shorter amount of time.

Considering the Fed, it's likely
2018Bearish PatternsbubbleS&P 500 E-Mini FuturesshortSPX (S&P 500 Index)SPDR S&P 500 ETF (SPY)

Also on:

Disclaimer