How Much Debt a Company Should Carry Has No Settled Answer
Theory says the mix of debt and equity should not matter, then adds back taxes, bankruptcy costs, and incentives until it clearly does. What survives is a set of considerations rather than a formula.
The Starting Point
The foundational result states that under specified conditions, no taxes, no bankruptcy costs, no information asymmetry, the value of a company does not depend on how it is financed.
The intuition is that the company value comes from its assets and the cash they generate. Dividing the claims on that cash between debt holders and equity holders changes who receives what, not how much there is.
The result is useful precisely because its conditions are false. It tells you that capital structure can only matter through taxes, distress costs, or incentives, which is where to look.
What Makes Debt Attractive
Interest is generally deductible against taxable profit while dividends are not. That creates a tax shield: a company paying interest reduces its tax bill, and the value of that saving accrues to shareholders.
Taken alone this implies companies should be financed almost entirely with debt, which is obviously wrong, so something must offset it.
What Limits It
| Cost of debt | Mechanism |
|---|---|
| Financial distress | Probability of failure rises with leverage |
| Indirect distress costs | Customers, suppliers, staff leave before failure |
| Underinvestment | Distressed firms skip good projects |
| Loss of flexibility | Cannot respond to opportunity or shock |
Indirect costs are larger than they appear. A company perceived as financially weak loses customers worried about warranty and support, suppliers tighten terms, and employees leave. Those costs arrive well before any formal insolvency and can cause it.
The Trade Off View
Combining the two gives a target: increase debt until the marginal tax benefit equals the marginal expected cost of distress. That produces the prediction that stable, asset rich, profitable companies should carry more debt than volatile, intangible ones, which broadly matches observation.
It also predicts an optimum that companies should stay near, and companies do not obviously behave that way, which motivated a second view.
The Pecking Order View
This holds that companies prefer internal funds first, then debt, then equity last, because of what each signals.
Management knows more about the company than investors. Issuing equity when you believe the shares are undervalued harms existing holders, so a company issuing equity may be signalling that management thinks the price is high. Investors anticipate this and mark the price down on announcement, which is what tends to happen.
Debt suffers less from this problem because its value is less sensitive to what management knows. Internal funds avoid it entirely.
What Practitioners Actually Do
Surveys consistently find that companies prioritise financial flexibility and credit ratings above calculating an optimal ratio. They maintain capacity to borrow rather than using it, so that they can act when opportunities appear and survive when conditions deteriorate.
That is not a failure to apply theory. Preserving optionality has real value that a static trade off calculation does not capture.
The Bottom Line
Capital structure is irrelevant only under conditions that do not hold, and every real consideration, tax shields, distress costs, signalling, and flexibility, pushes in a different direction. There is no formula producing the right answer. Stable predictable businesses can support more debt, and the value of retaining unused capacity is the thing most often underweighted.