Is that not the commonly cited example for commodity trading, whereas meaningful comparison of fundamentals to market capitalization only started much later?

The idea is broadly similar, but I guess here's another example with a company this time.

https://en.wikipedia.org/wiki/Bengal_Bubble_of_1769

The point is that I don't think irrational exuberance in stocks is a recent thing.

Oh, they had those too back in the day: https://en.wikipedia.org/wiki/South_Sea_Company