This is a very retail oriented view of the world. For the big players it’s trivial to move stock any time of day, there are various methods, they aren’t sitting around waiting for financial markets to open.
Would you care to give some examples? Anything after hours must be OTC, but traders won’t be on the floor on Saturday and Sunday. I know. I was there. So, who’s going to trade during the weekend? Trades also have to be reported within a certain time. I’m not sure about weekend reporting. It’s a genuine question. Your comments seems more a hearsay than actual experience.