%0 Journal Article %A Michael D. Carpenter %A David E. Upton %T Trading Volume and Beta Stability %D 1981 %R 10.3905/jpm.1981.408797 %J The Journal of Portfolio Management %P 60-64 %V 7 %N 2 %U https://jpm.pm-research.com/content/iijpormgmt/7/2/60.full.pdf