I saw this on twitter and figured that I want to test this out. I have very little experience with Jewish holiday type of seasonality. I got my dates from this website. http://www.timeanddate.com/holidays/us/rosh-hashana. As you may know I based my testing on 1st profitable opening or close and 2.5% stop loss with long or short trades. Between Rosh Hashana and Yom Kippur, I managed to get 77% chance of winning (Excluding the currently open trade) but with a negative expectation. Since 1995, there are only 4 times that market went up between Rosh Hashana and Yom Kippur but those 4 times greatly exceeded my 2.5% stop.
However, there are quite a few negative signals triggered recently, this one just might add to the bearish case. I would not act on this signal alone though.