Earnings announcements and the variability of stock returns

Abstract

This paper is concerned with the dissemination process of firm-specific annual earnings information in the Norwegian capital market. We find a significant reduction in stock price volatility in the post-announcement period relative to the pre-announcement period for companies traded on the Oslo Stock Exchange in the period 1990-1995. Potential explanations for this phenomenon are tested by relating the observed return volatility to changes in the volatility of the underlying business, the speed at which information is incorporated into stock prices, and the amount of noise in the price process. The empirical analyses reveal no significant changes in either the underlying business variance or the price adjustment coefficients. However, we find a significant decline in the noise term for the largest companies after the earnings release date, supporting the hypothesis that earnings announcements reduce informational asymmetries among investors.