The basic assumptions of MM theory are: 1. The company only has the long-term bonds and common stocks, both bonds and stock trade in the complete capital market with no transaction cost; 2. The individual investors and corporate investors could gain the same interest rate with no liability risk; 3. The companies with similar operating conditions have the same business risks; 4. Investors hold the same expectations on the average business profit in future; 5. All cash flows are perpetual annuities, including EBIT (Earnings before interest and tax) etc, that is, the growth rate of the enterprise is zero (Modigliani and Miller 1958).
The development of MM theory mostly experienced three stages: 1. No-tax model. The first MM model takes no account of corporate taxations; 2. Corporate tax model. Modigliani and Miller (1963) published Corporate Income Taxes and the Cost of Capital: A Correction, which loosened its initial assumptions, introduced corporate tax into MM theory(Modigliani and Miller 1963); 3. Miller model. Merton H. Miller (1976) proposed to consider corporate tax and individual tax in estimating how the debt leverage impacts the value of firm (Miller 1977).
During the past 50-year, MM theory has made tremendous academic achievements for western companies in exploring the optimal capital structure and reducing capital costs etc. Firstly, it provides a research frame of
References: Huang, G. and F. M. Song (2006). "The Determinants of Capitral Structure: Evidence from China." China Economic Review 17(1): 23. Huang, S. and G. Zhang (2007). "The Analysis of Financing Preference on China 's Listed Companies." Economic Research Journal 42(472): 12. Miller, M. H. (1977). "Debt and Taxes " presidential address delivered at the annual meeting of the American Finance Association, September 17, 1976. Journal of Finance. Modigliani, F. and M. H. Miller (1958). "The Cost of Capital, Corporation Finance and the Theory of Investment " The American Economic Review 48(3): 38. Modigliani, F. and M. H. Miller (1963). "Corporate Income Taxes and the Cost of Capital: A Correction." The American Economic Review 53(3): 11.