Abstract. This study establishes and tests, within the framework of a noisy rational expectations equilibrium model, the existence of a formal linear relationship between security prices, the average (consensus) and the dispersion of agents' expectations. Variations in the average and in the dispersion of agents' expectations, measured by the earnings forecasts produced by financial analysts, which are gathered and made available by The Institutional Brokers Estimate System (I/B/E/S), have respectively a positive and negative effect on security prices. The difficulties raised by this estimation, as well as the institutional dimensions of the financial analysis industry are examined. The main results are the following: (1) the most important changes in consensus (in absolute value) correspond to the most important changes in dispersion in the analysts' forecasts, (2) the changes in the consensus and the dispersion of forecasts are respectively positively and negatively linked to Canadian security returns, but given the delay between the production and the public availability of the forecasts, an important part of the price adjustment occurs before the disclosure of forecast changes, (3) the effect on security returns of variations in the consensus dominates the effect of variations in the forecasts' dispersion. Thus, it seems that the impact of information arrival on security prices does not only depend on the direction and the magnitude of the expectations' average revision, but also depends on the direction and the magnitude of the change in the expectations' dispersion.