The Relationship between Return and Market Value of Common Stocks*

This study examines the empirical relattonship between the return and the total market value of NYSE common stocks. It is found that smaller firms have had htgher risk adjusted returns, on average, than larger lirms. This ‘size effect’ has been in existence for at least forty years and is evidence that the capital asset pricing model is misspecttied. The size elfect is not linear in the market value; the main effect occurs for very small tirms while there is little difference m return between average sized and large firms. It IS not known whether size per se is responsible for the effect or whether size IS just a proxy for one or more true unknown factors correlated with size.