Apple often gains (or loses) more than $50B in a day. It also happens to be slightly down about 0.15% since July 19th, compared to a total market fund that would be up about 0.15%.
I honestly don't pay much attention to Apple stock (hello, availability bias!), so I'm curious how often it does that. Assuming that day's move was just noise, though, should we conclude that it's unrelated to the AI bubble? That there is no AI bubble? Something else?
I suggest the prior to any question about recent stock price movements should be “random walk”.
The random walk is an emergent phenomenon, though. It arises from the individual movements, but doesn't explain them. That's a bit like saying "Traffic" when someone asks, "Why are all these people out driving today?"