In
finance
Finance is the study and discipline of money, currency and capital assets. It is related to, but not synonymous with economics, the study of production, distribution, and consumption of money, assets, goods and services (the discipline of fina ...
, the capital structure substitution theory (CSS) describes the relationship between earnings, stock price and
capital structure
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 ...
of public companies. The CSS theory hypothesizes that managements of public companies manipulate capital structure such that
earnings per share
Earnings per share (EPS) is the monetary value of earnings per outstanding share of common stock for a company. It is a key measure of corporate profitability and is commonly used to price stocks.
In the United States, the Financial Accounting ...
(EPS) are maximized. Managements have an
incentive to do so because shareholders and analysts value EPS growth. The theory is used to explain trends in capital structure,
stock market valuation,
dividend policy Dividend policy is concerned with financial policies regarding paying cash dividend in the present or paying an increased dividend at a later stage. Whether to issue dividends, and what amount, is determined mainly on the basis of the company's una ...
, the
monetary transmission mechanism, and
stock volatility, and provides an alternative to the
Modigliani–Miller theorem
The Modigliani–Miller theorem (of Franco Modigliani, Merton Miller) is an influential element of economic theory; it forms the basis for modern thinking on capital structure. The basic theorem states that in the absence of taxes, bankruptcy costs ...
that has limited descriptive validity in real markets. The CSS theory is only applicable in markets where
share repurchases are allowed. Investors can use the CSS theory to identify undervalued stocks.
The formula
The CSS theory assumes that company managements can freely change the capital structure of the company – substituting
bonds for
stock
In finance, stock (also capital stock) consists of all the shares by which ownership of a corporation or company is divided.Longman Business English Dictionary: "stock - ''especially AmE'' one of the shares into which ownership of a company ...
or vice versa – on a day-to-day basis and in small denominations without paying transaction costs. Companies can decide to buy back one single share for the current market price P and finance this by issuing one extra corporate bond with face value P or do the reverse. In mathematical terms these substitutions are defined as
where D is the corporate debt and n the number of shares of company x at time t. The negative sign indicates that a reduction of the number of shares n leads to a larger debt D and vice versa. The earnings-per-share change when one share with price P is
repurchased and one bond with face value P is
issued:
# The earnings that were ‘allocated’ to the one share that was repurchased are redistributed over the remaining outstanding shares, causing an increase in earnings per share of:
# The earnings are reduced by the additional interest payments on the extra bond. As interest payments are tax-deductible the real reduction in earnings is obtained by multiplying with the tax shield. The additional interest payments thus reduce the EPS by:
Combining these two effects, the marginal change in EPS as function of the total number of outstanding shares becomes:
where
* E is the earnings-per-share
* R is the nominal interest rate on corporate bonds
* T is the
corporate tax
A corporate tax, also called corporation tax or company tax, is a direct tax imposed on the income or capital of corporations or analogous legal entities. Many countries impose such taxes at the national level, and a similar tax may be imposed at ...
rate
EPS is maximized when substituting one more share for one bond or vice versa leads to no marginal change in EPS or: