[jklein11]

Out of curiosity, why ~20?

[quantumhobbit]

P/E ratios are around 20 on average I suppose. Meaning earnings are 5% of the market cap of a stock.

GDP doesn't directly correlate to earnings though.

[ThrustVectoring]

Historically, $20 is the price of something that gives you $1/year. This, like, goes back to the medieval era.

[arjunnarayan]

It's just a rule of thumb as to what long run P/E ratios look like in the equity markets.