Also found in: Encyclopedia, Wikipedia.
An economic theory stating that the investment decisions of a firm are independent from the firm's owner's wishes. The Separation Theorem states that the productive value of a firm's management neither affects nor is affected by the owner's business decisions. As a result, the performance of a firm's investments has no relation to how they are financed, whether by stock, debt, or cash. The theorem was devised by economist Irving Fisher. See also: Irrelevance result.