Call volumes

This chart really gives away the game.

Option trading started to go mainstreet after covid and it's gone fully parabolic in the last few months. Yes, it's a worrisome sign for the bulls but there is also a secular story here of option buying that's expanding multiples and exaggerating the market moves of hot stocks.

I'd argue this chart matters more than an chart of P/Es, at least in the short term.

Source: Investing Live