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Insider trading and portfolio structure in experimental asset markets with a long lived asset
(1997)
We report results of a series of nine market experiments with asymmetric information and a fundamental value process that is more "realistic" than those in previous experiments. Both a call market institution and a continuous double auction mechanism are employed. We find considerable pricing inefficiencies that are only partially exploited by insiders. The magnitude of insider gains is analyzed separately for each experiment. We find support for the hypothesis that the continuous double auction leads to more efficient outcomes. Finally, we present evidence of an endowment effect: the initial portfolio structure influences the final asset holdings of experimental subjects.
This paper examines intraday stock price effects and trading activity caused by ad hoc disclosures in Germany. The evidence suggests that the observed stock prices react within 90 minutes after the ad hoc disclosures. Trading volumes take even longer to adjust. We find no evidence for abnormal price reactions or abnormal trading volume before announcements. The bigger the company that announces an ad hoc disclosure, the less severe is the abnormal price effect following the announcement. The number of analysts is negatively correlated to the trading volume effect before the ad hoc disclosure. The higher the trading volume on the last trading day before the announcement, the greater is the price effect after the ad hoc disclosures and the greater the trading volume effect. Keywords: ad hoc disclosure rules, intraday stock price adjustments, market efficiency.