In corporate finance, capital structure refers to the mix of various forms of external funds, known as capital, used to finance a business. It consists of shareholders' equity, debt (borrowed funds), and preferred stock, and is detailed in the company's balance sheet. The larger the debt component is in relation to the other sources of capital, the greater financial leverage (or gearing, in the United Kingdom) the firm is said to have. Too much debt can increase the risk of the company and reduce its financial flexibility, which at some point creates concern among investors and results in a greater cost of capital. Company management is responsible for establishing a capital structure for the corporation that makes optimal use of financial leverage and holds the cost of capital as low as possible. Capital structure is an important issue in setting rates charged to customers by regulated utilities in the United States. The utility company has the right to choose any capital structure it deems appropriate, but regulators determine an appropriate capital structure and cost of capital for ratemaking purposes. Various leverage or gearing ratios are closely watched by financial analysts to assess the amount of debt in a company's capital structure. The Miller and Modigliani theorem argues that the market value of a firm is unaffected by a change in its capital structure. This school of thought is generally viewed as a purely theoretical result, since it assumes a perfect market and disregards factors such as fluctuations and uncertain situations that may arise in financing a firm. In academia, much attention has been given to debating and relaxing the assumptions made by Miller and Modigliani to explain why a firm's capital structure is relevant to its value in the real world. Basic concepts Leverage Up to a certain point, the use of debt (such as bonds or bank loans) in a company's capital structure is beneficial. When debt is a portion of a firm's capital structure, it permits the company to achieve greater earnings per share than would be possible by issuing equity. This is because the interest paid by the firm on the debt is tax-deductible. The reduction in taxes permits more of the company's operating income to flow through to investors. The related increase in earnings per share is called financial leverage or gearing in the United Kingdom and Australia. Financial leverage can be beneficial when the business