On a day like today, my 25% cash is holding me back. That's the price of being conservative.
In terms of absolute dollars, I remember my worst day loss was $80K, sometime in the midst of the Great Recession. The best day gain was $40K, but I cannot remember when that was. I am getting old. I have a daily record going back to 1999, so can find it if I want to. But I definitely remember telling myself that the market never goes up in a day as much as it drops. The ratio of max down vs up was around 2, for me anyway.
Anyway, my holdings are more conservative now. Even so, I still find it interesting to compare my winners and losers for the day to see if I can understand why, as they never move completely in unison. Usually, a stock moves along with its sector, which may be driven by some economic news. Or there might not be any rhyme or reason to it.
Even on a day like today, one of my positions dropped 2%. Why? Then, I remember that yesterday it went up 6% due to a good news. So, today investors like to chase something else and might have sold this to raise money. Funny stuff!
PS. By the way, you are not even 40 yet, if I recall correctly. Having that investable account at your age is darn impressive. I did not pay attention when at that age, but do not think I had more than 1/2 of what you have now. Probably quite a bit less than 1/2. But wait! A dollar was worth more then.