To what do market externalities lead? Responses Greater inefficiency in the market as it ignores the benefits or costs which encroach on third parties through activity in that market. Greater inefficiency in the market as it ignores the benefits or costs which encroach on third parties through activity in that market. Greater inefficiency in the market as it accounts for costs or benefits which encroach on third parties through activity in that market. Greater inefficiency in the market as it accounts for costs or benefits which encroach on third parties through activity in that market. Greater efficiency in markets as it ignores the benefits or costs which encroach on third parties through activity in that market Greater efficiency in markets as it ignores the benefits or costs which encroach on third parties through activity in that market Greater efficiency in markets as it accounts for costs or benefits which encroach on third parties through activity in that market