Fisher separation theorem

The Fisher separation theorem states that, with perfect capital markets, a firm can choose investments to maximize its market value independently of its owners’ consumption preferences.

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Net present value: The present value of an investment’s expected cash inflows minus its costs. Accepting every positive-net-present-value project is the investment rule that supports separation.
Perfect capital market: An idealized market with frictionless trading, shared information, and no taxes or transaction costs. Frictionless borrowing and lending are central assumptions behind the theorem.
Irving Fisher: An American economist whose work shaped theories of interest, capital, and monetary economics. Fisher formulated the separation principle in his analysis of investment and consumption over time.
Capital budgeting: The process of evaluating and selecting long-term investments by an organization. The theorem supports evaluating projects by their contribution to firm value rather than owners’ personal preferences.
Credit rationing: A situation in which borrowers cannot obtain desired loans even when willing to pay higher interest rates. Restricted borrowing prevents owners from freely adjusting consumption after firm investment decisions.
Capital market: A market where financial claims such as stocks and bonds are issued and traded. The theorem depends on owners being able to trade across time at a common market rate.
Present value: The current worth of future cash flows, discounted to reflect time and risk. The firm’s value is assessed by discounting the cash flows its investments generate.
The Theory of Interest: Irving Fisher’s 1930 book analyzing interest rates, capital, and choices between present and future income. Fisher presented the separation argument as part of his theory of intertemporal investment.
Shareholder wealth maximization: A corporate objective of increasing the market value of shareholders’ claims. Value maximization follows when owners can tailor their own consumption through capital markets.
Asymmetric information: A condition in which parties to a transaction have different information about relevant facts. Unequal information can make financing choices affect project selection and firm value.