Here is a script to know when big dumps, and pumps, are happening.
Meant for crypto (I know that's what most people are interested in - it's a mistake) and small caps.
Might work for other things have not checked.
With some random small cap:
"When the majority of people extrapolate the past in a bull cycle and expect the future to be the same, they usually are right and we are pretty early in the cycle"
- Warren Dalio