Herd behavior and contagion in financial markets

Imitative behavior and contagion are well-documented regularities of financial markets. We study whether they can occur in a two-asset economy where rational agents trade sequentially. When traders have gains from trade, informational cascades arise and prices fail to aggregate information dispersed among traders. During a cascade all informed traders with the same preferences choose the same action, i.e., they herd. Moreover, herd behavior can generate financial contagion. Informational cascades and herds can spill over from one asset to the other, pushing the price of the other asset far from its fundamental value

Herd behavior and contagion in financial markets

We study a sequential trading financial market where there are gains from trade, that is, where informed traders have heterogeneous private values. We show that an informational cascade (i.e., a complete blockage of information) arises and prices fail to aggregate information dispersed among traders. During an informational cascade, all traders with the same preferences choose the same action, following the market (herding) or going against it (contrarianism). We also study financial contagion by extending our model to a two-asset economy. We show that informational cascades in one market can be generated by informational spillovers from the other. Such spillovers have pathological consequences, generating long-lasting misalignments between prices and fundamentals

Transaction costs and informational cascades in financial markets: theory and experimental evidence

We study the effect of transaction costs (e.g., a trading fee or a transaction tax, like the Tobin tax) on the aggregation of private information in financial markets. We analyze a financial market à la Glosten and Milgrom, in which informed and uninformed traders trade in sequence with a market maker. Traders have to pay a cost in order to trade. We show that, eventually, all informed traders decide not to trade, independently of their private information, i.e., an informational cascade occurs. We replicated our financial market in the laboratory. We found that, in the experiment, informational cascades occur when the theory suggests they should. Nevertheless, the ability of the price to aggregate private information is not significantly affected

Herd behavior in financial markets: an experiment with financial market professionals

We study herd behavior in a laboratory financial market with financial market professionals. An important novelty of the experimental design is the use of a strategy-like method. This allows us to detect herd behavior directly by observing subjects' decisions for all realizations of their private signal. In the paper, we compare two treatments: one in which the price adjusts to the order flow in such a way that herding should never occur, and one in which the presence of event uncertainty makes herding possible. In the first treatment, subjects seldom herd, in accordance with both the theory and previous experimental evidence on student subjects. A proportion of subjects, however, engage in contrarianism, something not accounted for by the theory. In the second treatment, the proportion of herding decisions increases, but not as much as the theory would suggest. Moreover, contrarianism disappears altogether. In both treatments, in contrast with what theory predicts, subjects sometimes prefer to abstain from trading, which affects the process of price discovery negatively

Information Cascades: Evidence from An Experiment with Financial Market Professionals

Previous empirical studies of information cascades use either naturally occurring data or laboratory experiments with student subjects. We combine attractive elements from each of these lines of research by observing market professionals from the Chicago Board of Trade (CBOT) in a controlled environment. As a baseline, we compare their behavior to student choices in similar treatments. We further examine whether, and to what extent, cascade formation is influenced by both private signal strength and the quality of previous public signals, as well as decision heuristics that differ from Bayesian rationality. Analysis of over 1,500 individual decisions suggests that CBOT professionals are better able to discern the quality of public signals than their student counterparts. This leads to much different cascade formation. Further, while the behavior of students is consistent with the notion that losses loom larger than gains, market professionals are unaffected by the domain of earnings. These results are important in both a positive and normative sense.

Thought and Behavior Contagion in Capital Markets

Prevailing models of capital markets capture a limited form of social influence and information transmission, in which the beliefs and behavior of an investor affects others only through market price, information transmission and processing is simple (without thoughts and feelings), and there is no localization in the influence of an investor on others. In reality, individuals often process verbal arguments obtained in conversation or from media presentations, and observe the behavior of others. We review here evidence concerning how these activities cause beliefs and behaviors to spread, affect financial decisions, and affect market prices; and theoretical models of social influence and its effects on capital markets. Social influence is central to how information and investor sentiment are transmitted, so thought and behavior contagion should be incorporated into the theory of capital markets.capital markets; thought contagion; behavioral contagion; herd behavior; information cascades; social learning; investor psychology; accounting regulation; disclosure policy; behavioral finance; market efficiency; popular models; memes

Herd Behavior in Financial Markets: An Experiment with Financial Market Professionals

We study herd behavior in a laboratory financial market with financial market professionals. An important novelty of the experimental design is the use of a strategy-like method. This allows us to detect herd behavior directly by observing subjects’ decisions for all realizations of their private signal. In the paper, we compare two treatments: one in which the price adjusts to the order flow in such a way that herding should never occur, and one in which the presence of event uncertainty makes herding possible. In the first treatment, subjects herd seldom, in accordance with both the theory and previous experimental evidence on student subjects. A proportion of sub jects, however, engage in contrarianism, something not accounted for by the theory. In the second treatment, the proportion of herding decisions increases, but not as much as the theory would suggest. Moreover, contrarianism disappears altogether. In both treatments, in contrast with what theory predicts, subjects sometimes prefer to abstain from trading, which affects the process of price discovery negatively.Herding, Contrarianism, Financial Market Professionals

Path-Dependent Behavior with Asymmetric Information about Traders' Types

We define path-dependency as the generic phenomenon according to which agents take an action regardless of their private information. Path-dependency can be of two types contingent on whether agents act with the crowd (herding) or against the crowd (contrarianism). We consider a quote-driven market where traders can in some cases observe whether their predecessors were informed, although they cannot observe their private information, while in other cases they are left with the uncertainty that their predecessors acted purely for liquidity motives. In this setting we recover herding and contrarianism and we find that better-informed markets (i.e. where informed traders receive high precision signals) can generate path-dependent behavior more easily than poorly informed ones. Moreover, we illustrate how a market dominated by herding features a price that is more informative of the asset value than the price of a market where traders always follow their signal. We also discuss how contrarianism has the exact opposite effect by decreasing price informativeness

Herd Behavior in Financial Markets: An Experiment with Financial Market Professionals

We study herd behavior in a laboratory ?nancial market with ?- nancial market professionals. An important novelty of the experi- mental design is the use of a strategy-like method. This allows us to detect herd behavior directly by observing subjects?decisions for all realizations of their private signal. In the paper, we compare two treatments - one in which the price adjusts to the order ?ow in such a way that herding should never occur, and one in which the presence of event uncertainty makes herding possible. In the ?rst treatment, traders herd seldom, in accordance with both the theory and previous experimental evidence on student subjects. A proportion of traders, however, engage in contrarianism, something not accounted for by the theory. In the second treatment, on the one hand, the proportion of herding decisions increases, but not as much as the theory would sug- gest; on the other hand, contrarianism disappears altogether. In both treatments, in contrast with what theory predicts, subjects sometimes prefer to abstain from trading, which a¤ects the process of price discovery negatively.

Herding and price convergence in a laboratory financial market

We study whether herding can arise in a laboratory financial market in which agents trade sequentially. Agents trade an asset whose value is unknown and whose price is efficiently set by a market maker. We show that the presence of a price mechanism destroys the possibility of herding. Most agents follow their private information and prices converge to the fundamental value. This result contrasts with the case of a fixed price, where herding and cascades arise. When the price moves, however, agents may behave as contrarian, i.e., they may trade against the market, something not accounted for by the theory. Finally, we study whether informational cascades arise when trade is costly (e.g, because of a Tobin tax). With trade costs, most subjects rationally decided not to trade and the price was unable to aggregate private information efficiently