Informational Externalities and Welfare-Reducing Speculation
分析投机者进入市场如何影响价格的信息含量，对已有交易者造成外部性，即使所有参与者理性且风险厌恶，也可能导致价格不稳定和福利下降。
Introducing more speculators into the market for a given commodity leads to improved risk sharing but can also change the informational content of prices. This inflicts an externality on those traders already in the market, whose ability to make inferences based on current prices will be aff ected. In some cases, the externality is negative: the entry of new s peculators lowers the informativeness of the price to existing trader s. The net result can be one of price destabilization and welfare red uction. This is true even when all agents are rational, risk-averse c ompetitors who make the best possible use of their available informat ion. Copyright 1987 by University of Chicago Press.