Again, let's look at the actual numbers and not just some fantasy numbers pulled out of thin air. I use the cash close at 4:00 PM as my closing value and 09:30 AM as my opening value.
1. For 2021, the actual percentage of gaps up is 57 %. The average gap is + 3,25, so there is a positive skew.
2. Assuming you're actually filled at the open/close and
ignoring transaction costs, the cumulative tally of buying the close and selling the open is + 220,75.
Maximum drawdown is 15,25 points which happened early in the year. Note: The drawdown have been severe in prior perioods.
That's over 67 trading days so far this year.
3. So, how does this compare to simple buy and hold?
So far this year and using Friday's Close @ 4119,25 and the Open the 4th of January @ 3758,50 - the result is 360,75 points, i.e., outperforming the Midnight Rally by 140 points.
Accounting for transaction costs; it will be even more significant. And since the Midnight Rally is an overnight strategy, one can't assume extra leverage being employed compared with buy and hold.
TL;DR - The Midnight Rally is profitable so far this year with low drawdown, but it vastly underperforms simple buy and hold which is to be expected during a trending market which sees gains both overnight and in the cash session (61 % of this year's sessions closed higher than they opened).