Capital Structure: Modigliani-Miller for Small Business
Capital Structure: Modigliani-Miller for Small Business
Modigliani and Miller proved that, in a frictionless world, how a business is financed does not change what it is worth. The world has frictions. In a worked example, a business worth $10 million with no debt is worth about $10.75 million with $6 million of debt, as tax savings outweigh expected distress costs, and less again with $8 million. For small businesses, personal guarantees, pass-through taxes and scarce equity change every term of that trade-off.
What you'll learn
The irrelevance result
In 1958, Franco Modigliani and Merton Miller proved a result that still anchors corporate finance: under ideal conditions, how a business is financed does not change what it is worth. A firm's value comes from the cash its assets generate. Splitting that cash between lenders and owners in different proportions changes who gets what and how risky each claim is, but not the size of the total. If borrowing were cheaper than equity in some deep sense, investors could borrow on their own account and undo any advantage.
The ideal conditions are the point. No taxes, no costs of financial distress, no differences in information between managers and investors, and no frictions in borrowing. Every reason capital structure matters in practice is a departure from one of those assumptions, which is why the theorem is better read as a map of where value can be created or lost through financing than as a claim that financing never matters.
Why cheap debt is not a free lunch
The intuition most people bring to financing is that debt is cheaper than equity, so more debt lowers the cost of capital. Modigliani and Miller's second proposition shows why that is wrong in a frictionless world. As a firm borrows more, its equity becomes riskier, and owners rationally demand a higher return to hold it. With a 10% return required on the business's assets and a 6% cost of debt:
| Debt to equity | Required return on equity | Weighted cost of capital |
|---|---|---|
| 0 | 10% | 10% |
| 0.5 | 12% | 10% |
| 1.0 | 14% | 10% |
| 1.5 | 16% | 10% |
The cheaper debt is exactly offset by more expensive equity. Each dollar shifted from equity to debt saves the difference in rates but raises the risk, and so the required return, on every remaining dollar of equity. Per our moral hazard analysis, owners of highly leveraged firms also gain incentives to take risks lenders would not accept, which lenders price in, and per our bankruptcy analysis, the costs of resolving default are among the frictions that make the irrelevance result fail in practice.
Taxes and the cost of distress, worked
Take a business with $1,000,000 of annual operating profit and a 10% required return on its assets, so it is worth $10,000,000 with no debt. In 1963 Modigliani and Miller added corporate taxes: because interest is deductible, permanent debt creates a tax shield worth roughly the tax rate times the debt. At a 21% rate, $4,000,000 of debt adds about $840,000 of value. Debt also raises the chance of financial distress, which destroys value through lost customers, distracted management and legal costs. Assume distress would cost 30% of firm value.
| Debt | Tax shield value | Probability of distress | Expected distress cost | Firm value |
|---|---|---|---|---|
| $0 | $0 | 0% | $0 | $10,000,000 |
| $2,000,000 | $420,000 | 1% | $31,260 | $10,388,740 |
| $4,000,000 | $840,000 | 4% | $130,080 | $10,709,920 |
| $6,000,000 | $1,260,000 | 15% | $506,700 | $10,753,300 |
| $8,000,000 | $1,680,000 | 35% | $1,226,400 | $10,453,600 |
This is the trade-off theory. It predicts that firms with stable cash flows and tangible assets, which are cheap to finance and cheap to recover in distress, should borrow more, and firms whose value depends on growth opportunities or intangible assets should borrow less. Per our debt overhang analysis, part of the distress cost is the good investments an overhung firm stops making.
Information and the pecking order
Myers and Majluf added asymmetric information. Owners know more about their business than outside investors. A firm offering new equity signals that its owners think the shares are worth less than the price, so investors discount new equity heavily. Debt, whose value is less sensitive to what insiders know, suffers less of that discount, and internal cash suffers none.
- Retained earnings first, because they require convincing no one.
- Debt next, because lenders care mainly about downside protection.
- Outside equity last, because it invites the largest discount.
Myers called this the pecking order. Per our signaling analysis, the same logic explains why collateral and owner investment carry information to lenders.
What changes for small businesses
- Limited liability is often fictional. Per our personal guarantee analysis, small business debt usually carries a personal guarantee, so the owner bears distress costs directly and the trade-off is personal as well as corporate.
- Taxes work differently. Most small businesses are pass-through entities, so interest reduces the owner's taxable income at personal rates. Larger businesses face a cap on interest deductions under federal tax law, from which businesses under an inflation-adjusted gross receipts threshold are generally exempt. Per our small business tax analysis, the shield is real but depends on the owner's situation.
- Outside equity is often unavailable. Robb and Robinson found that new firms relied heavily on external debt, including bank loans and owner-backed credit, rather than outside equity, the reverse of the common image of venture-funded startups.
- Information gaps are largest. Per our debt contract analysis, the cost of verifying a small firm's cash flows is what makes simple debt the dominant contract.
- Owner pay blurs the line. Per our owner compensation analysis, owners choose between salary, distributions and retained earnings in ways that change both taxes and the balance sheet lenders see.
Using the framework
- Ask what the financing changes, not just what it costs. Debt that funds a project creating value is different from debt that only shifts risk between owner and lender.
- Count distress costs honestly. Per our business failure analysis, small businesses fail more often than larger ones, and a guarantee puts those costs on the owner.
- Match debt to assets. Tangible, saleable assets support more borrowing; per our business value analysis, lenders value what they could recover.
- Keep retained earnings working. The pecking order suggests internal funds are the cheapest capital, which is also why lenders value businesses that retain profit.
The counter-case
The theories explain averages, not decisions
Empirical tests of capital structure theories are mixed. Many profitable firms borrow less than the trade-off theory suggests, which the pecking order explains, but small growth firms issue equity when the pecking order says they should borrow. Firms also adjust leverage slowly and appear to time equity issues to market conditions. For small businesses, financing is often constrained by what lenders will offer rather than chosen optimally, so the relevant question may be how to expand options rather than which option to pick. Per our growth cash analysis, many owners discover their capital structure by running out of cash rather than by design.
Testable implications
- Leverage should rise with asset tangibility and cash flow stability across otherwise similar firms.
- More profitable small firms should carry less debt, as the pecking order predicts, because they fund themselves internally.
- Firms facing higher marginal tax rates should use more debt, unless distress costs are high.
- Owners with personal guarantees should choose lower leverage than the trade-off theory predicts for an equivalent firm with genuine limited liability.
Frequently asked questions
Under ideal conditions, financing does not change a firm's value; real effects come from departures from those conditions.
Debt adds a tax shield but raises distress costs. In the example, value peaks at about $10.75 million with $6 million of debt.
Firms prefer retained earnings, then debt, then outside equity, because information gaps make outside equity costly.
Guarantees, pass-through taxes, scarce outside equity and large information gaps change the trade-offs for small firms.
Key takeaways
- Under ideal conditions, financing does not change a firm's value.
- Taxes, distress costs and information differences are why capital structure matters.
- In the example, value rises from $10 million unlevered to about $10.75 million at $6 million of debt, then falls.
- The pecking order favors retained earnings, then debt, then outside equity.
- Personal guarantees put distress costs on small business owners directly.
- Pass-through taxation and interest deduction limits change the value of the tax shield.
- New firms rely heavily on external debt rather than outside equity.
References
- Modigliani, F., & Miller, M. H. (1958). The Cost of Capital, Corporation Finance and the Theory of Investment. American Economic Review, 48(3), 261–297.
- Modigliani, F., & Miller, M. H. (1963). Corporate Income Taxes and the Cost of Capital: A Correction. American Economic Review, 53(3), 433–443.
- Myers, S. C. (1984). The Capital Structure Puzzle. Journal of Finance, 39(3), 574–592.
- Myers, S. C., & Majluf, N. S. (1984). Corporate Financing and Investment Decisions When Firms Have Information That Investors Do Not Have. Journal of Financial Economics, 13(2), 187–221.
- Robb, A. M., & Robinson, D. T. (2014). The Capital Structure Decisions of New Firms. Review of Financial Studies, 27(1), 153–179.
This analysis is educational and does not constitute investment, tax or legal advice. Operating profits, required returns, tax rates, distress probabilities and costs are stylized illustrations and do not describe any particular business. Tax treatment of interest depends on entity type, size and current law; consult a tax advisor.