Contemporary research documents various psychological aspects of economic decision making. The main goal of our study is to analyze the role of the availability heuristic Kahneman [1973, 1974]) in financial markets. The availability heuristic refers to people's tendency to determine the likelihood of an event according to the easiness of recalling similar instances and, thus, to overweight current information as opposed to processing all relevant information. We define and test two aspects of the availability heuristic, which we dub outcome and risk-availability. The former deals with the availability of positive and negative investment outcomes and the latter with the availability of financial risk. We test the availability effect on investors' reactions to analyst recommendation revisions. Employing daily market returns as a proxy for outcome availability, we find that positive stock price reactions to recommendation upgrades are stronger when accompanied by positive stock market index returns, and negative stock price reactions to recommendation downgrades are stronger when accompanied by negative stock market index returns. The magnitude of the outcome availability effect is negatively correlated with firms' market capitalization, and positively correlated with stock beta, as well as with historical return volatility. Regarding risk availability, we find that on days of substantial stock market moves, abnormal stock price reactions to upgrades are weaker, and abnormal stock price reactions to downgrades are stronger. Both availability effects remain significant even after controlling for additional company-specific and event-specific factors, including market capitalization, stock beta, historical volatility of stock returns, cumulative excess stock returns over one month preceding the recommendation revision, rating category before the revision, and number of categories changed in the revision.

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Human judgments are systematically affected by various biases and distortions. The main goal of our study is to analyze the effects of five well-documented behavioral biases—namely, the disposition effect, herd behavior, availability heuristic, gambler’s fallacy and hot hand fallacy—on the mechanisms of stock market decision making and, in particular, the correlations between the magnitudes of the biases in the cross-section of market investors. Employing an extensive online survey, we demonstrate that, on average, active capital market investors exhibit moderate degrees of behavioral biases. We then calculate the cross-sectional correlation coefficients between the biases and find that all of them are positive and highly significant for both professional and non-professional investors and for all categories of investors, as classified by their experience levels, genders, and ages. This finding suggests that an investor who is more inclined to employ a certain intuitive decision-making technique will most likely accept other techniques as well. Furthermore, we determine that the correlation coefficients between the biases are higher for more experienced investors and male investors, indicating that these categories of investors are likely to behave more consistently, or, in other words, are more likely to decide for themselves whether to rely on simplifying decision-making techniques in general or to reject all of them. Alternatively, this finding may suggest that these investors develop more sophisticated “adaptive toolboxes”, or collections of heuristics, and apply them more systematically

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