I agree with everything you said except for one thing in 5 (d). I have also seen stocks gap up bigtime only for the pps to flatline for the rest of the day. I think this would take out the day traders as they cannot make any gains trading a stock that doesn't fluctuate in price. We can only speculate as to who was doing the buying and who was selling in such a tight range.It could be some funds unloading some and some other,new or exsting, funds buying. The MMs are able to and can keep the price steady to facilitate the buying and selling.
This is only an educated guess on my part. I think the MMs and funds view the stock market as their turf and wouldn't want retail making any money long term or by day trading. Flatlining a stock that has very good reason to fluctuate a lot in a single day would keep the day traders away.
The MMs and funds also like to relieve retail of their shares by dropping the pps 3-5% on very little volume only to see the pps shoot back up very shortly. We have seen this many times with CDMO recently. JMO.
One note, The pros and the pros are two. The pro's in the first and last hours are executing brokers that open overnight positions and close day-trader positions.
The pros open the market and are usually done in the first hour unless it's an unusual market day. Jr. traders take over and hold the ship steady till the pros return in the last hour. Just watching the minute chart, when the pros came back, buying picked up again.
A second 'kind' of pro are the pro-traders vs the semi-pro and amatory traders. They are active in that window that you described. Machine trading for instance avoid the less controllable open and close unless there is a good reason to do otherwise.
So far for that, and it is an educated opinion.
About that capping at 29,50% that took place yesterday.
A) I neither do believe that the ATM was running
B) This capping is not intentional (e.g. against CDMO) but consequential (filling algo's)
C) Very often, without ignoring exceptions that confirm the rule, such massive machine action is a signal of something to come (in good or in bad). Hence the flat trading doesn't give away which one it is.
D) The AH followed by yesterdays PH trading and opening volume and price, seem to indicate that it is something good and the S&P 600 kind of the positive cause.
E) I also don't believe every gap gets closed. So now there is you, a poster you referred and me, so one more and we can play cards :)