Big Ideas

Didier Sornette has an interest in financial markets as examples of complex systems. He authored Why Stock Markets Crash : Critical Events in Complex Financial Systems, published in November 2002. He has maintained on his web site for several years a series of predictions regarding the behavior of the S&P 500 index. In initiating this series, he wrote:

“Based on a theory of cooperative herding and imitation working both in bullish as well as in bearish regimes that we have developed in a series of papers, we have detected the existence of a clear signature of herding in the decay of the US S&P 500 index since August 2000 with high statistical significance, in the form of strong log-periodic components.”

His September 2002 paper (with Wei Zhou) entitled “The US 2000-2002 Market Descent: How Much Longer and Deeper?” provides a detailed justification of this assertion, including a comparison of the 1990 Japanese and 2000 U.S. stock market crashes. The evolution of Professor Sornette’s predictions is as follows: Keep Reading

Nassim Taleb’s central theme in Fooled by Randomness (the 2004 second edition) is that noise generally swamps signal (true outperformance or underperformance) in financial markets, and in life generally. A standard deviation much larger than an associated average excess return, encountered consistently in the search for outperforming investing/trading strategies, is an indicator of such swamping. The book effectively uses corollaries and examples to reinforce Nassim Taleb’s contention that past performance is neither a guarantee of future returns nor a proof of either intelligence or stupidity. Rather than recount his arguments, we focus this review on his conclusions as they relate specifically to speculating in financial markets. These conclusions are: Keep Reading

Professor Aswath Damodaran of the Leonard Stern School of Business at New York University offers on his web site a broad and deep set of financial education materials covering: corporate finance, investment (portfolio) management and valuation. He presents considerable information from his books, such as Investment Philosophies and Investment Fables, including supporting data. For example… Keep Reading

In his March 2005 paper entitled “Reconciling Efficient Markets with Behavioral Finance: The Adaptive Markets Hypothesis”, Andrew Lo presents a framework for unifying the Efficient Markets Hypothesis (EMH) and Behavioral Finance. The paper is thoughtful and thought-provoking. Some key points are: Keep Reading

In The Anglosphere Challenge: Why the English-Speaking Nations Will Lead the Way in the Twenty-First Century, James Bennett implicitly advises focusing investments in certain countries. As depicted in the figure below, Mr. Bennett’s main thesis points are that: Keep Reading

In their February 2005 paper entitled “Portfolio Concentration and the Performance of Individual Investors,” Zoran Ivkovic, Clemens Sialm and Scott Weisbenner test the dictum for diversification by examining the stock trades of a large number of individuals during 1991-1996 through a discount broker. They find that: Keep Reading

In his June 2004 paper on “What Are Stock Investors’ Actual Historical Returns”, Ilia Dichev examines stock market capital inflows and outflows to determine how well investors really perform compared to buy-and-hold returns. He concludes that: Keep Reading

Triumph of the Optimists: 101 Years of Global Investment Returns by Dimson, Marsh and Staunton (2002) is thorough, logical and concise. With scores of illustrative graphs and figures, its statistics are accessible and its style straightforward. Its message, however, is somewhat at odds with the title. Below is a chapter-by-chapter review of the insights in this book: Keep Reading

Do stock index prices fluctuate around some value baseline? In his March 2001 paper entitled “Temporary Movements in Stock Prices”, Jonathan Lewellen investigates the degree to which stock market returns exhibit long-term reversion. Using data from the period 1926-1998, he concludes that: Keep Reading

In his April 2003 working paper entitled “The Efficient Market Hypothesis and Its Critics”, Burton Malkiel, author of A Random Walk Down Wall Street, contends that “a blindfolded chimpanzee throwing darts at the Wall Street Journal could select a portfolio that would do as well as the experts.” Has recent work of the behavioral finance community and the pattern-finders changed his mind? Keep Reading