What it means
Every business needs money to buy assets and run its operations. That money comes from two broad sources: debt (borrowed money that must be repaid with interest) and equity (money from owners, including retained profits).
The proportion of each is the capital structure. Debt is usually cheaper than equity because lenders accept lower returns in exchange for being paid first.
Interest on debt is also often tax deductible, which lowers its real cost. However, debt must be repaid on schedule, so too much of it raises the risk of financial trouble in a downturn.
Equity is more expensive because shareholders expect higher returns for taking more risk, but it has no fixed repayment date. A business with a high share of equity can survive a bad year more easily.
A business with a high share of debt can earn bigger returns for owners in good years, an effect known as financial leverage, but it can also suffer more in bad years. There is no single perfect mix.
Stable businesses with predictable cash flow, such as utilities, can carry more debt, while young or volatile businesses usually rely more on equity. Finance teams look at ratios such as debt to capital and debt to equity to track the balance over time.
Capital structure decisions are made by the board and finance leadership. They affect borrowing terms, the cost of capital, dividend policy and the company's flexibility to raise funds when it needs them.
Lenders often set limits on leverage in loan agreements, so the structure is also constrained by outside parties. Capital structure also affects the day-to-day running of a business.
A company with heavy debt must keep enough cash to pay interest and principal on time, which limits how much it can invest in new projects. A company with more equity has room to spend on growth but may face questions from investors about whether it is using its funding efficiently.
In practice
Real-world examples
Example 1
A software company with steady subscription revenue borrows $2,000,000 to fund an acquisition instead of selling more shares. Its debt share rises from 10% to 30% of total capital. The founders keep more of the ownership.
Example 2
A utility company funds a new power line with 60% debt and 40% equity because its regulated income is predictable. Lenders are comfortable with the high proportion of debt. A similar project at a start-up would be considered far too risky.
Example 3
A retail chain struggling with weak sales has too much borrowing. The board agrees to sell new shares worth $5,000,000 and use the money to repay loans. The debt share falls, and the company is able to renegotiate its credit terms.
Think of it
Capital structure is like deciding how to finance a house-how much to put down versus borrow. The mix affects your costs and risks.
Formula
Calculation
Debt to capital ratio = Total debt / (Total debt + Total equity)
Worked example: a company has $4,000,000 of debt and $6,000,000 of equity.
Step 1: Total capital = $4,000,000 + $6,000,000 = $10,000,000.
Step 2: Debt share = $4,000,000 / $10,000,000 = 0.40, or 40%.
Step 3: Equity share = $6,000,000 / $10,000,000 = 60%.
The capital structure is 40% debt and 60% equity. The debt to equity ratio is $4,000,000 / $6,000,000 = 0.67, or about two-thirds.Case study
Seen in the real world
Bluewater Logistics is an illustrative, fictional freight company funded with $3,000,000 of equity and $1,000,000 of debt, a debt share of 25%. The owners wanted to buy more trucks and had two options: raise new equity or borrow. They chose to borrow $2,000,000.
The new capital structure was $3,000,000 of equity and $3,000,000 of debt, a 50% debt share. Returns to owners improved while freight volumes were high. A fall in demand a year later made the interest payments hard to meet, and the lenders asked for a tighter covenant.
The illustrative lesson is that borrowing can lift returns but also removes the safety margin. The board now reviews the debt share each quarter against a target range. Looking back, the owners agreed that the right question was not how much they could borrow, but how much borrowing the business could survive in a weak year.
Watch out
Common mistakes
- Believing more debt is always better because it is cheaper than equity, when it also raises the risk of default.
- Using book values only and ignoring the market value of equity when judging the mix.
- Assuming there is one ideal capital structure that suits every business.
Questions
People also ask
What is a healthy debt to equity ratio?
It depends on the industry, with stable sectors tolerating more debt than volatile ones, so compare against similar companies.
Does capital structure include short-term debt?
Often yes, though some analysts focus only on long-term debt and equity, so check the definition used.
Who sets the capital structure?
The board and senior finance leaders decide, within the limits set by lenders, regulators and investors.
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