Les marchés financiers sont-ils rationnels ?
Due to the recent stock market crises, many economists have been keeping aloof from the « core» of financial theory, whose main contention is that stock market prices are at any moment the best possible estimate of the « true» value of the issuing firms. Most of those economists have brought forward, in a way or another, the hypothesis that markets suddenly get crazy. This contribution, based on both observa~tion of the recent financial history (the crash of the « New Economy» securities) and results from « experimental economics», and using the complementary concepts of « mimicry» and « convention » to account for « self-referential dynamics», is opening a third way of thinking the efficiency problematic: investors fix their strategy based on the estimates of the other participants, even if they strongly believe they are wrong.
Price Bubbles in Laboratory Asset Markets with Constant Fundamental Values
We construct asset markets that are similar to those studied by Smith, Suchanek and Williams (Econometrica. 56, 1119–1151) in which bubbles and crashes tended to occur. The main difference between the markets studied here and those studied by Smith et al. is that in the markets studied here, the fundamental value of the asset is constant over the entire life of the asset. In four of the eight sessions reported here, we observe bubbles, which are prices considerably higher than fundamental values. The data suggest that the frequent payment of dividends is a major cause of bubble formation. The property that the fundamental value remains constant over the course of the trading horizon is not sufficient to eliminate the possibility of a bubble.
Price bubbles and crashes in experimental call markets
Abstract Price bubbles relative to intrinsic dividend value are observed using a call market trading institution. Market prices tend to track intrinsic value only when the same group of highly experienced traders participate in three consecutive 15-round markets.