Information in Securities Markets: Kyle Meets Glosten and Milgrom

This paper analyzes models of securities markets with a single strategic informed trader and competitive market makers. In one version, uninformed trades arrive as a Brownian motion and market makers see only the order imbalance, as in Kyle (1985). In the other version, uninformed trades arrive as a Poisson process and market makers see individual trades. This is similar to the Glosten–Milgrom (1985) model, except that we allow the informed trader to optimize his times of trading. We show there is an equilibrium in the Glosten–Milgrom‐type model in which the informed trader plays a mixed strategy (a point process with stochastic intensity). In this equilibrium, informed and uninformed trades arrive probabilistically, as Glosten and Milgrom assume. We study a sequence of such markets in which uninformed trades become smaller and arrive more frequently, approximating a Brownian motion. We show that the equilibria of the Glosten–Milgrom model converge to the equilibrium of the Kyle model.     

关于“身份盗窃”行为的入罪化思考

＂身份盗窃＂行为的日益普遍造成了巨大的现实危害,现行刑法的制裁体系严重滞后。依赖于＂招摇撞骗罪＂和＂伪造公司、企业、事业单位、人民团体印章罪,伪造、变造身份证罪＂的制裁体系,虽然在客观上可以部分实现对于＂身份盗窃＂行为的刑事制裁,但这一体系的形成,更多地不是一种立法的主观追求,而是一种意外形成的立法效果。深入思考和研究＂身份盗窃＂行为对于传统刑事立法的冲击和对于传统刑法理论的挑战,逐步实现＂身份盗窃＂行为的独立入罪化,已经越来越有必要。