RT Journal Article SR Electronic T1 The Theory of Punctuated Equilibrium JF The Journal of Portfolio Management FD Institutional Investor Journals SP 1 OP 1 DO 10.3905/jpm.15.3.1 VO 15 IS 3 A2 Peter L. Bernstein YR 1989 UL https://pm-research.com/content/15/3/1.abstract AB