Patterns of Concentration in Private Pension Plan Common Stock Portfolios since ERISA
研究了1974年《雇员退休收入保障法》(ERISA)对私人养老金计划普通股投资组合集中度的影响，发现ERISA后养老金计划的资产集中度下降，但分散化程度仍低于市场组合。
Several provisions of the Employee Retirement Income Security Act of 1974 (ERISA) have significant implications for the investment policies of private pension plans. To test the effects of ERISA on the common stock portfolios of private pension plans, the portfolios of 1,700 plans were examined and compared portfolios of bank trust departments and mutual funds. Asset concentration ratios have declined since ERISA for pension plans but not for bank trust departments or mutual funds. Pension portfolios display much less diversification than the market portfolio, and the plans concentrate their investments in common stocks relatively high market values. The Employee Retirement Income Security Act of 1974 (ERISA) imposes on private pension plans a complex regulatory framework governing all major aspects of their operations. The sections of the Act the most significant implications for investment operations are those fiduciary responsibility. Fiduciaries under ERISA are required to act with the care, skill, prudence, and diligence under the circumstances then prevailing that a prudent man acting in a like capacity and familiar such matters would use in conducting an enterprise of like character and like aims. 1 This differs from the traditional prudent man rule, which judges the fiduciary by the standard of a prudent man dealing his own property. The traditional rule applied to each security in the portfolio, and fiduciaries were not permitted to offset losses in one segment of the portfolio against gains in other segments [ 1]. Under the ERISA rule, on the other hand, prudence is meant to J. David Cummins is Professor of Insurance and Associate Director of the S.S. Huebner Foundation for Insurance Education at the University of Pennsylvania Wharton School. He earned his Ph.D. at the University of Pennsylvania. Dr. Cummins has published extensively in major refereed journals, is the author of several books, and is the editor of Investment Activities of Life Insurance Companies. Randolph Westerfield is Professor of Finance at the University of Pennsylvania Wharton School. He has a Ph.D. from the University of California at Los Angeles. Dr. Westerfield has published several articles in academic journals such as the Journal of Finance and the Journal of Financial and Quantitative Analysis. The authors thank Scott Harrington and Sandra Gustavson for their helpful comments and suggestions on an earlier version of this article. Of course, any errors or omissions are the sole responsibility of the authors. The research on which this article is based was conducted for the United States Department of Labor under contract no. J-9-P-6-0209. The conclusions expressed in the article are those of the authors and not of the Department of Labor. Employee Retirement Income Security Act of 1974, secs. 401-414.