The days when the indexes drop 2% or more during the day are painful.
Here is a quick study on $SPY and $QQQ since 2017. Long at open the day after 2%+ drop from intraday high to close. So we buy at open and sell at close the next day after 2%+ red day.
Up most of the times during the trading hours on the next day… $QQQ seems to be more rebound ready. This week feels like the red can continue forever.