Trading based on forecasts of earnings per share: A test of the efficient market hypothesis

In this paper the semi-strong form of the efficient market hypothesis is tested with a trading rule based on Box-Jenkins forecasts of earnings per share numbers. The quarterly earnings per share series are modeled for a number of firms. The models are updated quarter by quarter and investments are made in the stocks with the largest forecasted growth rates for the next quarter. The risk-adjusted performance of such a strategy is shown to be inconsistant with semi-strong market efficiency.