Updated for the 2026-2027 CFA® Level I curriculum.
A company's capital structure is not a fixed choice. It shifts as business risk, financing needs, and stakeholder pressure change over time. CFA Level I candidates need to explain what pushes a company toward more debt or more equity, and how those shifts affect the weighted-average cost of capital. This note builds a practical framework for that reasoning, then connects to the dedicated notes on cost of capital and Modigliani-Miller for the underlying math.
Quick Answer
Capital structure is shaped by business risk, operating and financial risk, company life-cycle stage, financing needs, and the competing interests of lenders and shareholders. More debt raises financial risk and the cost of equity, but it can lower WACC only up to a point. Beyond that point, rising default risk pushes both the cost of debt and WACC higher.
Key Takeaways
Capital structure is the mix of debt and equity a company uses to fund operations, and it changes as company circumstances change.
Business risk (from industry and operations) and financial risk (from debt) combine to determine total company risk.
Early-stage companies typically rely more on equity because they lack stable cash flow to support debt.
Mature companies with predictable cash flow can typically support more debt at lower cost.
Lenders prefer lower leverage for safety. Shareholders may prefer more leverage to increase potential returns.
Adding debt lowers WACC only while the tax benefit outweighs rising financial risk. Past that point, WACC rises.
A common mistake is assuming more debt always reduces WACC. It does not.
What You Need to Know for CFA Level I
Identify the main factors that influence a company's choice between debt and equity financing.
Explain how business risk and financial risk each contribute to a company's overall risk profile.
Describe how financing needs and access to capital change across the company life cycle.
Explain how stakeholder interests, particularly those of lenders and shareholders, can push capital structure in different directions.
Explain, in general terms, how changes in capital structure affect WACC without needing to perform the WACC calculation itself.
What Factors Affect Capital Structure?
Capital structure decisions respond to a small set of recurring factors. The table below summarizes the main ones tested at Level I.
Factor | Typical Effect on Capital Structure |
|---|---|
Business risk | Higher business risk limits how much debt a company can safely add. |
Financial risk | Existing debt levels affect how much additional debt is prudent. |
Company life-cycle stage | Early-stage companies lean on equity. Mature companies can support more debt. |
Cash flow stability | Stable, predictable cash flow supports higher debt capacity. |
Access to capital markets | Limited market access can force reliance on whatever financing is available. |
Stakeholder preferences | Lenders favor conservative leverage. Shareholders may favor more leverage. |
Tax considerations | Interest expense is tax-deductible, which can make debt cheaper on an after-tax basis. |
No single factor determines capital structure alone. Candidates should treat these as inputs that interact, not a checklist applied in isolation.
Business Risk, Operating Risk, and Financial Risk
Business risk and financial risk affect a company in different ways, but they are closely connected. For CFA Level I, the key is understanding where each type of risk comes from and how operating and financing decisions can increase a company’s overall risk.
Business Risk and Operating Risk
Business risk is the uncertainty in a company’s operating income, driven by factors such as industry conditions, demand variability, and cost structure.
A company with high fixed costs relative to variable costs has higher operating risk because changes in revenue can create larger changes in operating income. This is the concept behind the degree of operating leverage, which measures how sensitive operating income is to changes in sales.
For CFA Level I, focus on the concept and direction of this relationship. The detailed degree of operating leverage formula and calculation belong to a separate study note.
Financial Risk From Debt
Financial risk comes from fixed financing costs, primarily interest payments on debt.
A company with high operating risk that also carries substantial debt faces compounded risk because both operating and financing costs are relatively fixed. If revenue falls, the company must still cover these costs, increasing the risk of financial distress.
How Business Risk Affects Debt Capacity
Companies with higher business risk generally have less capacity to take on additional financial risk through debt.
Adding debt to an already high level of operating risk can raise the required returns demanded by both debt and equity investors. As a result, the higher cost of financing may offset some of the tax benefits associated with debt.
How Company Life Cycle and Financing Needs Affect Capital Structure
Financing needs change as a company matures.
Startup stage. Cash flow is unpredictable and often negative. Equity financing, including funding from founders or venture investors, is typically the main source of capital since lenders are unwilling to extend debt against uncertain cash flow.
Growth stage. Revenue is expanding but still variable. Companies may begin adding modest debt as cash flow becomes more visible, while continuing to rely heavily on equity to fund expansion.
Mature stage. Cash flow is stable and predictable. These companies can typically support higher debt levels at lower cost, since lenders view the cash flow as reliable collateral for repayment.
Decline stage. Revenue may be shrinking. Companies in this stage often reduce debt capacity as lenders reassess default risk, even if the company previously supported higher leverage.
This life-cycle pattern explains why capital structure is not static. A company's optimal mix of debt and equity shifts as its risk profile and cash flow stability change.
How Stakeholder Interests Affect Financing Decisions
Lenders and shareholders can view the same financing decision differently because they bear different risks and receive different benefits. For CFA Level I, focus on how these competing interests can influence a company’s use of debt and equity.
What Lenders Prefer
Lenders prioritize repayment certainty. They generally favor lower leverage, stronger cash flow coverage, and covenants that limit additional borrowing.
As existing debt increases, lenders bear greater default risk. They may respond by demanding higher interest rates or stricter lending terms.
What Shareholders Prefer
Shareholders may prefer more leverage, within reasonable limits. Debt can increase potential returns on equity when the return earned on borrowed funds exceeds the cost of debt.
Issuing debt also avoids diluting existing shareholders’ ownership through new equity issuance. However, excessive leverage increases financial risk, so management must balance shareholder preferences with lender concerns and the company’s ability to service its debt.
How Capital Structure Changes Can Affect WACC
Changes in debt and equity financing can affect a company’s weighted-average cost of capital. The key relationship is that moderate debt may reduce WACC, while excessive debt can eventually push it higher.
Why Debt Can Initially Lower WACC
Debt is typically cheaper than equity, and interest expense is generally tax-deductible. As a result, adding a reasonable amount of debt can reduce the company’s overall weighted-average cost of capital.
This benefit is one reason companies may use debt alongside equity rather than relying entirely on equity financing.
Why Too Much Debt Can Increase WACC
The benefit of additional debt does not continue indefinitely. As leverage increases, financial risk rises.
Lenders may demand higher interest rates to compensate for greater default risk, while shareholders may require higher returns because their equity has become riskier. Beyond a certain point, these higher required returns can outweigh the tax benefit of additional debt, causing WACC to rise.
For this study note, focus on the direction of the relationship rather than the full WACC calculation. Candidates who need the formula and calculation process should review the dedicated Weighted-Average Cost of Capital study note.
Common Exam Traps
Treating capital structure as fixed
Some candidates memorize a single "ideal" debt-to-equity ratio. Capital structure is a moving target that responds to business risk, life-cycle stage, and financing conditions.
Assuming more debt always lowers WACC
This is true only while the tax benefit of debt outweighs the added financial risk. Past that point, more debt raises WACC.
Confusing operating risk with financial risk
Operating risk comes from the cost structure of the business. Financial risk comes from the use of debt financing. They compound each other but are not the same source of risk.
Reintroducing DOL and DFL calculations as the main point
This note focuses on the direction and interpretation of risk factors, not on calculating the degree of operating leverage or degree of financial leverage. Those calculations belong to separate notes.
Ignoring stakeholder conflict
Candidates sometimes assume management picks capital structure in isolation. Lender covenants and shareholder return expectations both constrain the decision in practice.
Practice Question
A mid-sized manufacturing company has stable, predictable cash flow, moderate existing debt, and easy access to bank financing. Its management is deciding whether to fund a new plant expansion with additional debt or a new equity issuance.
Which factor most strongly supports using additional debt rather than equity for this expansion?
The company operates in an industry with highly variable demand.
The company's cash flow is stable and predictable.
The company's shareholders want to avoid any dilution of ownership regardless of cost.
Correct Answer: B
Stable, predictable cash flow supports higher debt capacity because lenders view reliable cash flow as a strong basis for repayment. This is the clearest, most defensible factor favoring debt in this scenario.
Option A. Highly variable demand indicates high business risk, which would argue against adding more debt, not for it.
Option C. Avoiding dilution is a shareholder preference, but "regardless of cost" ignores the risk of over-leveraging, making this a weaker and less complete justification than stable cash flow.
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FAQs About Factors Affecting Capital Structure and WACC
Does more debt always lower a company's WACC?
No. Debt is typically cheaper than equity and interest is tax-deductible, so moderate debt can lower WACC. Beyond a certain point, rising default risk increases both the cost of debt and the cost of equity, which raises WACC instead.
Why do early-stage companies rely more on equity than debt?
Early-stage companies often have unpredictable or negative cash flow, which makes lenders unwilling to extend debt. Equity investors accept this uncertainty in exchange for potential upside.
What is the difference between business risk and financial risk?
Business risk comes from the uncertainty of operating income, driven by industry and cost structure. Financial risk comes from the use of debt financing and the fixed obligation to pay interest.