Taking Asymmetric Information Seriously: Protecting Price Formation on Financial Markets

Abstract

This paper studies the problem of asymmetric information that exists in financial markets between the public and the market makers, that is, the securities dealers who support the stability of asset prices by carrying inventory over short periods of time. Market makers in modern markets typically have access to information about a broad range of markets and trade on the basis of this information. While trade on fundamental information about the value of assets is necessary for asset prices to be informative, trade on market information, such as the presence in the market of a highly motivated seller, often does not make prices more informative. Modern regulation in the U.S. has generally taken a permissive approach both to trading on market information, and also to the proliferation of conflicts of interest that increase profit opportunities from trading on market information. This paper critiques this regulatory approach by explaining that economic theory does not in general indicate that there are efficiency gains from permitting trading on market information, by describing an alternate model of a financial market, the pre-1986 London Stock Exchange which required dealers to avoid conflicts of interest and limited trading on market information by not making public the size of trades, and by discussing recent scandals that illustrate the costs of trading on market information.

The costs and benefits of trading on market information are very difficult to measure because of the absence of benchmark prices against which the prices that are observed in markets can be compared. One proxy for measuring the net costs of such trading is the aggregate cost of financial intermediation: if this falls during a time period when conflicts of interest and opportunities to trade on market information have increased, then one might conclude that the consequences of trading on such information are unlikely to be large. In fact, over the relevant time period there was a dramatic increase in the costs of financial intermediation. While recognizing that the evidence offered here of social cost created by trading on market information is far from conclusive, this paper proposes two policies that could mitigate such costs: a requirement that market makers avoid conflicts of interest, and the non-release of some intraday market data to reduce the market information on which trade can take place.