Do investors value the voluntary assurance of sustainability information? Evidence from the Spanish stock market

Abstract

AbstractThis study examines in the Spanish setting whether, after the passing of the European Directive 2014/95/UE, investors value positively the voluntary assurance of sustainability reports corresponding to the period 2014–2017 for a sample of listed companies. It also analyzes the valuation by investors of a series of assurance characteristics such as its quality, level of application (reasonable/high vs. moderate/limited), scope (complete vs. partial), and the type of assurance provider (accounting vs. non‐accounting firms). Our results find that investors reward firms that adopt external sustainability assurance. Furthermore, we document that investors value to a greater extent those assurance statements with a broader scope, a high/reasonable level of assurance, and with a better quality. Our results are relevant for companies, investors, regulators, and practitioners, and justify the pertinence of the recent Law 11/2018 that places Spain as a European reference by requiring a mandatory assurance of sustainability information in order to increase its reliability and comparability.