Introduction: Modigliani and Miller theorem is regarded as a milestone and a paradigm shift in Corporate Finance. The research behind the theorem has given rise to the controversial conclusion that a company's capital structure is irrelevant in an equilibrium market, without taxation. In contrast, when taxation occurs firm value will increase equivalent to the deductible tax on interest expense when debt is issued. The theorem has not been without criticism. Several researchers have examined the theorem and criticised its assumptions.
Purpose: The purpose of the study is to investigate the Modigliani and Miller theorem in respect of capital structure’s impact on companies' share prices.
Literature Review: The Modigliani and Miller theorem with its assumptions is initially presented as the study’s main theorem. The presentation of the theorem is followed by a description of agency theory, signalling theory, trade-off theory and the efficient market hypothesis, along with previous studies on the theorem and its assumptions.
Research Methodology: The study applies a quantitative approach, with three regression models. The random sample consists of ten companies in the industrial sector, that are listed on the Stockholm Stock Exchange. The sample is based on panel data of the companies during the period 2005 to 2012. The study's empirical data consists of historical stock prices and annual reports.
Empirical Results: The leverage ratio, i.e. debt to equity ratio, indicates a low and non-signif-icant correlation with the stock prices of the examined companies, in all three regression models. The tax shield indicates a higher and significant correlation with the stock price, while the control variable earnings per share EPS indicates the highest correlation with the stock prices, as the response variable.
Conclusions: The study’s results show no empirical support for the Modigliani-Miller theorem in its entirety. The explanation for the findings may be that the assumptions are not satisfied in the empirical data. Agency theory, signalling theory, trade-off theory and the efficient market hypothesis may serve as explanations of the study’s results.