There are some market inefficiencies that have been documented but they seem rare. The post earnings announcement drift (PEAD)[0] is a thing that exists but shouldn't if markets were totally efficient. That gets used for gains pretty consistently but not 100% of the time. Euan Sinclair had a book where he mentioned a return of 9-27% when traded on annually.[1]

Some of the big players have moves like that which work well given the right market conditions. My guess is that they have many, many patterns like that to trade on or models which are right more often than not. I don't know anything though since I'm a 101 retail investor... Positional options trading and volatility stuff makes my brain hurt :(

Have you seen strategies like that before? It's really interesting to dig into but seems to require a lot of knowledge to know how to trade on.

[0] https://en.wikipedia.org/wiki/Post%E2%80%93earnings-announce...

[1] Positional Options Trading: An Advanced Guide, pg. 90