Is it Beneficial to be Included in a Sustainability Stock Index? A Panel Data Study for European Firms

This paper empirically examines the effect of inclusion in the Dow Jones Sustainability World Index (DJSI World) on corporate financial performance. On the basis of panel data for European firms that were included in the Dow Jones Stoxx 600 Index over time, our micro-econometric analysis with fixed and random effects models implies positive impacts on return on assets for continental European countries, but insignificant effects for Anglo-Saxon European countries (i.e., the United Kingdom and Ireland). Furthermore, the impacts on alternative indicators of corporate financial performance such as Tobin’s Q are generally insignificant. The weak or neutral effect of inclusion in the DJSI World on corporate financial performance can be explained by several mutually confounding factors. Furthermore, the composition of this sustainability stock index is influenced by factors that need not necessarily be directly connected to corporate environmental or social activities, so that potential positive and negative effects of corporate sustainability performance on financial performance can be weakened. Methodologically, this study again supports the strong relevance of unobserved firm heterogeneity since the application of misspecified pooled regression models leads to obviously biased estimation results.