> Your definition of “winner” is someone who leaves money on the table No, my definition of winner (in a transaction) is someone who gives less than what they

> Your definition of “winner” is someone who leaves money on the table No, my definition of winner (in a transaction) is someone who gives less than what they receive. > By that definition there is no market where they are two winners. No, transactions can be positive sum if the goods & services being traded are valued differently by the buyer and seller. For example, if it costs me $2 for materials & $8 in labor to knit sweaters, I value each sweater at $10. Someone else who is using the sweater to stay warm, may value that sweater at $30. If we transact at $20, that's a positive sum transaction. However, equity markets are different because the "product" that's being traded (NPV of future company cash flows) isn't valued differently by various parties. That is, if the NPV of future company cash flows is $100, there's no party that will pay more than $100 for it. This invariance in valuation is the feature that gives rise to the zero sum nature of equity markets.