Abstract
A small to moderate size investment in company stock results in a relatively small increase in the riskiness of an employee’s portfolio, even if the company’s volatility is substantially greater than that of a diversified portfolio which we assume the employee would hold otherwise. Thus the employee suffers relatively little loss in “expected utility” from such an investment, whether or not the extra motivation due to this investment by the employee and his or her colleagues leads to an increase in productivity. However, increasing the investment beyond certain limits leads to substantial, and increasingly large, increments in the riskiness of the portfolio. This article presents the theory behind these assertions, and presents a plausible numerical example of the effects described. This example implies that the optimal investment in company stock in a diversified portfolio is \(8\frac{2}{3}\%\) while a higher amount of ten or even fifteen percent would not be imprudent.
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References
Blasi, J. R., & Kruse, D. L. (1991). The new owners: the mass emergence of employee ownership in public companies and what it means for American business. New York: Harper Collins Harper Business.
Blasi, J. R., Kruse, D. L., & Bernstein, A. (2003). In the company of owners. New York: Basic Books.
Blasi, J. R., Kruse, D. L., & Markowitz, H. (2008). Risk and lack of diversification under employee ownership and shared capitalism. Cambridge, Massachusetts: National Bureau of Economic Research working Paper 14229, August.
Dexter, A. S., Yu, J. N. W., & Ziemba, W. T. (1980). Portfolio selection in a lognormal market when the investor has a power utility function: computational results. In M. A. H. Dempster (Ed.), Stochastic programming (pp. 507–523). New York: Academic Press.
Ederington, L. H. (1986). Mean-variance as an approximation to expected utility maximization. Working paper 86-5, School of Business Administration, Washington University, St Louis, Missouri.
Employee Benefits Research Institute (2007). EBRI Issue Brief: 401(k) plan assets concentrated in equity funds. Washington, DC: Employee Benefits Research Institute (www.ebri.org) August.
Employee Benefits Research Institute (2008). EBRI advisory: EBRI resources on company stock in 401(k) plans. Washington, DC: Employee Benefits Research Institute (www.ebri.org) March.
Hlawitschka, W. (1994). The empirical nature of Taylor-series approximations to expected utility. The American Economic Review, 84(3), 713–719.
Kardas, P., Scharf, A., & Keogh, J. (2002). The wealth and income consequences of employee ownership. Oakland, CA: National Center for Employee Ownership.
Kelly, J. L. Jr. (1956). A new interpretation of information rate. Bell System Technical Journal, 917–926.
Kim, E., Kim, H., & Ouimet, P. (2008). Employee capitalism or corporate socialism: broad-based employee stock ownership, March 6, 2008. Available at Social Science Research Network (http://ssrn.com/abstract=1018552).
Kroll, Y., Levy, H., & Markowitz, H. M. (1984). Mean variance versus direct utility maximization. Journal of Finance, 39(1).
Kruse, D. L. (2002). Research evidence on prevalence and effects of employee ownership: testimony before the subcommittee on employer-employee relations. Committee on Education and the Workforce, US House of Representatives, February 13.
Kruse, D. L., Blasi, J. R., & Park, R. (2008). Shared capitalism in the US economy? Prevalence, characteristics, and employee views of financial participation in enterprises. Cambridge, Massachusetts: National Bureau of Economic Research working Paper 14225, August.
Latané, H. A. (1959). Criteria for choice among risky ventures. Journal of Political Economy, LXVII(2), 144–155.
Levy, H., & Markowitz, H. M. (1979). Approximating expected utility by a function of mean and variance. American Economic Review, 69(3), 308–317.
Lintner, J. (1965). The valuation of risk assets and the selection of risky investments in stock portfolios and capital budgets. Review of Economics and Statistics, 13–37.
Markowitz, H. M. (1952). Portfolio selection. The Journal of Finance, 7(1), 77–91.
Markowitz, H. M. (1956). The optimization of a quadratic function subject to linear constraints. Naval Research Logistics Quarterly, 3, 111–133.
Markowitz, H. M. (1959). Portfolio selection: efficient diversification of investments. New York: Wiley. Yale University Press (1970). 2nd edn. Basil Blackwell (1991).
Markowitz, H. M., & Todd, P. (2000). Mean-variance analysis in portfolio choice and capital markets. New Hope: Frank J. Fabozzi Associates. (Revised reissue with chapter by Peter Todd).
Markowitz, H. M., Reid, D. W., & Tew, B. V. (1994). The value of a blank check. The Journal of Portfolio Management, 82–91.
Pulley, L. M. (1981). A general mean-variance approximation to expected utility for short holding periods. Journal of Financial and Quantitative Analysis, 16, 361–373.
Pulley, L. M. (1983). Mean-variance approximations to expected logarithmic utility. Operations Research, 31(4), 685–696.
Roy, A. D. (1952). Safety first and the holding of assets. Econometrica, 20, 431–449.
Savage, L. J. (1954). The foundations of statistics. New York: Wiley. 2nd revised edn. Dover.
Sharpe, W. F. (1964). Capital asset prices: “A theory of market equilibrium under conditions of risk”. The Journal of Finance, 19(3), 425–442.
Simaan, Y. (1993). What is the opportunity cost of mean-variance investment strategies? Management Science, 39(5), 578–587.
Tobin, J. (1958). Liquidity preference as behavior towards risk. Review of Economic Studies, 25(1), 65–86.
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Markowitz, H.M., Blasi, J.R. & Kruse, D.L. Employee stock ownership and diversification. Ann Oper Res 176, 95–107 (2010). https://doi.org/10.1007/s10479-009-0544-1
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DOI: https://doi.org/10.1007/s10479-009-0544-1