MERTON MILLER'S CONTRIBUTIONS TO MODERN FINANCE

Winner of the 1990 Nobel Prize in Economics, and widely regarded as the “father of modern finance,” the University of Chicago's Merton Miller died last June at age 77. This article attempts to sum up Miller's career in terms of a single governing principle: the role of arbitrage in ensuring the “efficiency” of financial markets and, more generally, the effectiveness of such markets in promoting economic growth and creating social wealth. Starting with the formulation of Proposition I (also known as the capital structure irrelevance proposition) with Franco Modigliani in 1958, Miller's research over the next 40 years is seen as applying—with remarkable clarity and consistency—the principle of arbitrage to the study of many aspects of financial markets. Miller's main accomplishment, according to the author, is to have made arbitrage arguments the cornerstone of modern finance. The arbitrage proof of Proposition I introduced a new standard in finance—namely, that any finding in financial research deserving serious consideration must have the critical property that it cannot represent opportunities for riskless profit by investors. And the article goes on to show that arbitrage is a constant theme in Miller's writings, from his work in corporate finance to his later studies of financial innovation, derivatives markets, and financial crashes and crises. Having started and presided over the transformation of financial studies from a “glorified apprenticeship system” into a scientific discipline, Miller devoted much of the last 15 years of his life to a different, though clearly related undertaking: the defense of financial markets against the attacks of politicians and regulators, as well as businessmen intent on stifling competition (including hostile takeovers). Whether it was the alleged role of the stock index futures markets in the 1987 market crash, the claims of “overleveraging” in the LBOs of the '80s, or the derivatives fiascos in the mid‐'90s, Miller was there to provide careful economic analysis of the problems. In the early '90s, he explained why the “myopia” of the U.S. stock market was likely to cause far fewer problems than the “hyperopia” induced by regulatory distortions of the Japanese market. And in one of his last speeches, Miller showed that the primary cause of the recent Asian crisis was not “too much reliance on financial markets,” as claimed by politicians and the popular press, but “too little”—in particular, the heavy dependence on bank financing (particularly state‐owned banks) and the failure to develop alternative sources of capital that continue to depress the Japanese economy.