Investing in socially responsible mutual funds

We construct optimal portfolios of mutual funds whose objectives include socially responsible investment (SRI). Comparing portfolios of these funds to those constructed from the broader fund universe reveals the cost of imposing the SRI constraint on investors seeking the highest Sharpe ratio. This SRI cost crucially depends on the investor’s views about asset pricing models and stock-picking skill by fund managers. To an investor who strongly believes in the CAPM and rules out managerial skill, that is, a market index investor, the cost of the SRI constraint is typically just a few basis points per month, measured in certainty-equivalent loss. To an investor who still disallows skill but instead believes to some degree in pricing models that associate higher returns with exposures to size, value, and momentum factors, the SRI constraint is much costlier, typically by at least 30 basis points per month. The SRI constraint imposes large costs on investors whose beliefs allow a substantial amount of fund-manager skill, that is, investors who heavily rely on individual funds’ track records to predict future performance. ( JEL G11, G12, C11) In 2005, when we released what ultimately proved to be the final version of this study, socially responsible investment (SRI) had already become a major presence on the investment landscape. In the years since, this approach, now often called “sustainable” investment, has grown even more rapidly and often encompasses a broad set of “ESG” (environmental, social, and governance) criteria. As evidence of the rapid growth, Morningstar (2020) notes, “one need look no further than the nearly fourfold increase in assets that flowed into sustainable funds in the United States in 2019.” Sustainable investing has also received increased attention in the academic literature, in subsequent studies too numerous to list. Some of the studies are especially related to ours in that they also examine mutual funds. In our study, mutual funds constitute an asset universe faced by an investor imposing an SRI/ESG constraint. A number of the subsequent studies use mutual funds to address other dimensions of sustainable investing. For example, Bollen (2007), Benson and Humphrey (2008), Renneboog, Ter Horst, and Zhang (2011), Bialkowski and Starks (2016) and Hartzmark and Sussman (2019) investigate determinants of mutual fund flows into sustainable funds versus other funds. Riedl and Smeets (2017) use survey and experimental data to explore invest