We compute the correlations of the annual stock returns (1989-2008) of the Dow Jones companies with a) Rm; and with b) Rm; and find that the second correlation (assuming beta = 1 for all companies) is higher than the first one, on average, and for all companies except Caterpillar and General...

We report 2,510 answers from professors from 65 countries and 934 institutions. 1,791 respondents use betas, but 107 of them do not justify the betas they use. 97.3% of the professors that justify the betas use regressions, webs, databases, textbooks or papers (the paper specifies which ones),...

We calculate betas of 3,813 companies using 60 monthly returns each day of December 2001 and January 2002. The median (average) of the maximum beta divided by the minimum beta was 3.07 (15.7). The median of the percentage daily change (in absolute value) of the betas was 20%. Industry betas are...

It is a big mistake to use betas calculated from historical data to compute the required return to equity. It is a mistake for seven reasons: because betas calculated from historical data change considerably from one day to the next; because calculated betas depend very much on which stock index...