Chapter 17 · Van Horne, 13th Ed.

Capital Structure Determination

Quick MBA study notes — read in 10 minutes

1The Big Question

Capital structure is simply the mix of debt and equity a firm uses to finance itself. The chapter asks: does changing that mix actually change the value of the firm?

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Key Concept Three schools of thought answer this differently: the Net Operating Income (NOI) approach, the Traditional approach, and Modigliani & Miller (M&M).

Analogy: does slicing a pizza into 6 pieces instead of 8 change how much pizza there is? M&M says no — debt and equity are just different ways of slicing the same "pie" of firm value.

2Net Operating Income (NOI) Approach

Claims the firm's overall cost of capital (k_o) never changes with leverage — so total firm value never changes either.

V = O / k_o

Example

NOI = $1,000, k_o = 15% → Firm value = $6,667, regardless of how much debt is used.

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Key Concept As debt rises, k_e (cost of equity) rises just enough to offset the "cheap debt" benefit — so there is no optimal capital structure under this view.

3Traditional Approach

Argues an optimal capital structure does exist. Moderate debt lowers k_o because cheap debt outweighs the small rise in k_e. Beyond a point, k_e rises faster and k_o turns back up.

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Key Concept The optimal capital structure is the point where k_o is at its lowest — and firm value is at its highest.

4M&M's Total-Value Principle

In a world with no taxes and perfect markets, M&M prove that firm value is independent of capital structure. Investors can create "homemade leverage" by borrowing personally — so the firm can't do anything for them that they can't already do themselves.

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Key Concept Arbitrage keeps two otherwise-identical firms at the same total value — if a levered firm is priced higher, investors sell it and buy the unlevered one until prices converge.

Analogy: you can't get richer by rearranging how you personally split a fixed paycheck between "loan repayments" and "savings" — the total money is the same either way.

5Add Taxes: Debt Becomes Attractive

Once corporate taxes exist, interest is tax-deductible — debt creates a real "tax shield" that adds value.

Value (levered) = Value (unlevered) + (Debt × Tax Rate)

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Key Concept With only corporate taxes in the picture, firm value rises in a straight line as more debt is added — implying 100% debt would be "ideal." Real life disagrees — see below.

6Why Firms Don't Max Out on Debt

Two real-world costs push back against unlimited debt:

Bankruptcy costs — the risk (and cost) of financial distress rises sharply at high leverage
Agency costs — monitoring costs lenders and shareholders impose on management (covenants, audits) rise with debt too

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Key Concept The optimal capital structure is where the marginal tax-shield benefit of one more dollar of debt exactly equals the marginal bankruptcy + agency cost of that dollar.

7Financial Signaling

Managers know more about the firm's true prospects than outside investors do. Since they can't just announce "we're undervalued" credibly, they signal it through financing choices.

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Key Concept Issuing new debt is read by the market as "good news" (confidence in future cash flow). Issuing new stock is read as "bad news" (management thinks the stock is overvalued).

8Cheat-Sheet: The Three Views

Approach	Does capital structure matter?	Why
NOI	No	k_o stays constant; k_e rises to fully offset cheap debt
Traditional	Yes	Moderate debt lowers k_o before risk penalty kicks in
M&M (no tax)	No	Arbitrage/homemade leverage keeps firm value constant
M&M (with tax)	Yes	Tax shield adds value; bankruptcy/agency costs cap it

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Capital structure matters in the real world because taxes reward debt while bankruptcy and agency costs punish too much of it — the optimum sits where these forces balance.