Economic theory tells us that abnormal industry and firm profits will not persist for any length of time. Any industry or firm making profits in excess of the normal rate of return will attract entrants and this competitive process will erode profits. A substantial amount of research however,...

Economic theory tells us that abnormal firm and industry profits will not persist for any significant length of time. Any firm or industry making profits in excess of the normal rate of return will attract entrants and this competitive process will erode profits. However, a substantial amount of...