✔ Zero-sum game
A zero-sum game is a situation in which any gain by one side or person is at the expense of a loss to another side or person involved in the situation.
■ For example:
- The stock market has become a giant zero-sum game in which one investor gains what another investor loses.
- In a zero-sun game, if you add the total gains of the participants and the total losses of the participants, the sum will always be zero.
Origin: From game theory, a branch of applied mathematics that is used in the social sciences, especially economics.
Variety: This idiom is typically used in American English but may be used in other varieties of English too.