(By Darrel Whitten) Investments and Pensions Europe (IPE) is reporting on a paper called The Death of Common Sense by the so-called 300 Club, a group of 10 investment professionals formed to raise awareness of the impact of current market thinking, claims that CAPM (capital asset pricing model) and EMH (efficient market hypothesis actually contributed to the 2008 crash, even though both are the tenants of modern portfolio theory practiced by the majority of institutional investors. The inference of the pioneering work by Harry Markowitz, the annointed pioneer of modern investment theory, is that markets are efficient and that it is impossible to beat the market, which active investors to a man claim is simply untrue.
Modern innovations such as derivatives, shorting and high-frequency trading were justified as the only means to beat the market through clever mousetraps. But academics claim the main outcome has been increased systemic risk and growing complexity. The perfect storm was the massive fault in the market between 2002 and 2008, with excess liquidity in the global financial system and no chance for markets to correct.
CAPM and EMH critics claim that both describe a view of how financial markets work that is detached from grass roots reality. IPE readers reacted to the article by claiming that a) modern portfolio theory does not posit that CAPM/EMH were basis on which to manage portfolios, but theories and ways in which to identify some of the drivers of investment markets. The reality is that it is indeed extraordinarily difficult to beat the market consistently. The success of the models however depends on, (a) that most participants behave as if they do not believe in either one, and (b) that market conditions are 'normal,' without a concatenation of unusual or extreme events.
Good traders will immediately tell you that the "tails" of actual distributions are much fatter than the theoretical "normal" distribution curve, so that any risk model that basically assumes tail risk is small and unimportant as in a normal distribution is fatally flawed (ala John Meriwether's Long Term Capital Management), as was eloquently described in Taleb's Black Swan theory.
On the other hand, investment bankers love CAPM because manipulating the key inputs can "justify" just about any initial public offering price you want.