Where is Beta Going ? The Riskiness of Value and Small<br />Stocks

http://www.hec.fr/hec/fr/professeurs_recherche/upload/cahiers/CR829Franzoni.pdfThis paper finds that the market betas of value and small stocks have decreased by about 75% in the second half of the twentieth century. The path of beta can be closely tracked using conditioning variables that summarize the state of the economy. On the basis of this analysis, the decline in beta can be related to a long-term improvement in economic conditions that made these companies less risky. Decomposing beta into the cash flow and expected return news components confirms that the payoffs of these companies are less sensitive to market conditions. This finding has implications for the debate on the CAPM anomalies. The failure to account for time-series variation of beta in unconditional CAPM regressions can explain as much as 30% of the value premium. In some samples, about 80% of the value premium can be explained by assuming that investors tied their expectations of the riskiness of these stocks to the high values of beta prevailing in the early year