One aspect of the discussion about rational and irrational investors that is important to consider is the extent
to which professional traders and money managers are subject to the same behavioral biases that are more
commonly discussed in the context of individual (typically assumed uninformed) investors. A number of articles—
discussed here—consider this issue directly and find that professionals are far from immune to the biases. A full
description of these biases and the evidence for them is beyond the scope of this review. Readers who would like
a more detailed discussion should refer to Barberis and Thaler (2003) and Shefrin (2000).
Although the existence of behavioral biases among some investors is an essential component of behavioral
finance, a second essential strand relates to the limits to arbitrage. Traditional finance holds that if some (irrational)
investors misprice assets, the mispricing will be corrected by the trading actions of rational investors (arbitrageurs)
who spot the resulting profit opportunity, buy cheap assets, and sell expensive ones. Behavioral finance theory
counters that mispricing may persist because arbitrage is risky and costly, which has the result of limiting the
arbitrageurs’ demand for the fair-value restoring trades (Shleifer and Vishny 1997).
The existing academic literature has tended to develop behavioral finance against the “foil” of traditional
rational finance. But a number of authors (e.g., Statman 1999a; Thaler 1999) make the case for the “end of
behavioral finance,” arguing that because all financial theory requires some assumptions about investor behavior,
researchers should strive to make the best assumptions about behavior in all models rather than invent a subclass
of models featuring empirically observed behavior. Despite great strides in recent years, behavioral finance does
not appear to have reached the point of being considered in all models.
Investors seeking a more comprehensive introduction to the field are directed to the review articles by
Hirshleifer (2001) and Barberis and Thaler (2003) as well as to the relevant articles in the November/December
1999 issue of the Financial Analysts Journal. Shefrin’s (2000) book Beyond Greed and Fear is also recommended.
In the following sections, we discuss key areas in the application of behavioral finance. We discuss the limits
to arbitrage and then proceed to discuss behavioral asset pricing theory, behavioral corporate finance, and evidence
of individual investor behavior and behavioral portfolio theory. We also discuss briefly the psychology of risk,
ethics, and the emerging field of neuroeconomics. The final section of this review provides a bibliography with a
brief summary of each reference.
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