Abstract: he two main determinants of market efficiency are securities price accuracy and securities liquidity．The participants of the capital markets哪varied．but we can classify them simply into the following four types：informed traders(insiders)，information traders(securities analysts)，liquidity traders，and noise traders．Securities adopt the弛· strietion on insider trading，to entrust analysts with the role of providing efficient and liquid markets．Analysts can realize economies of scale and scope in searching，analyzing，and pricing general market information．The competition among analysts generates positive externalities for the information market and the investment banking industry．