There's nothing better that can be objectively measured. It's possible that everyone agrees a company's shares trading at $19 are worth ~$19 +/- a few cents, an

There's nothing better that can be objectively measured. It's possible that everyone agrees a company's shares trading at $19 are worth ~$19 +/- a few cents, and there would be no holdouts at all if you offered $20. You'll never know until you try to buy them all. You never really know the price of anything until a purchase is agreed to. A vast field of study exists to seek answers to the generalized form of the question you just asked: "What is the value of X?" I don't know anybody who is entirely satisfied with any of the "answers" the field of economics has given us to that question, so I doubt any answer you get here will really satisfy you, either.