How to assess/research companies at all time highs or lows?

Hey yall, I’m relatively new to investing (3 years now doing low risk investing) and would love some advice. What strategies do you use to assess companies at an all time high or an all time low?

If a company is at an all time high, what strategies do you use to predict (obvious no way to tell the future and know forsure) if this is the peak and it’ll go back down or if it’s going to keep growing? Same for the contrary if a company is at its lowest, determining whether it may bounce back up or just keep falling.

I’d like to use two examples of companies i am looking at (though I’d prefer for this thread to remain more conceptual rather than start bickering over the companies I’m using as an example):

• Waste Management — they are a strong company that is near all time highs. How do i assess if there is more growth to come in a company like this or if this is just a peak? What do i look for when i read through their data?

• Liberty Media — they have a few decent, profitable companies under them and Warren Buffet recently took a big stake in them but they’ve taken a nosedive this year and live nation has plenty of legal troubles. How do i research if this is just a trough and if they have the potential to bounce back vs just declining even further?

Thanks in advance for any advice yall may be able to give! Again, i hope to keep this discussion general with general tips on how to do this research. I’m not looking for arguments into Waste Management or Liberty Media (they were just examples of companies at all time highs and lows!)