Short-Term Investment and the Informational Efficiency of the Market

Abstract

A dynamic finite-horizon market for a risky asset with a continuum of risk-averse heterogeneously informed investors and a risk-neutral competitive market-making sector is examined. The article analyzes the effect of investors' horizons on the information content of prices. It is shown that short horizons enhance or reduce accumulated price informativeness depending on the temporal pattern of private information arrivaL With concentrated arrival of information, short horizons reduce final price informativeness; with diffuse arrival of information, short horizons enhance it. In the process a closed-form solution to the dynamic equilibrium with long-term investors is derived. In this article I study dynamic trading in a world where privately informed speculators are risk averse and have short horizons, and where the market is informationally (semi-strong) efficient due to the presence of a competitive risk-neutral market-making sector.