PurposeThe aim of the paper is to investigate whether social disclosure and environmental disclosure have a substituting or a complementing effect in reducing information asymmetry between managers and stock market participantsDesign/methodology/approachThis study attempts to provide a comprehensive analysis of a firm's social and environmental disclosure strategy. The authors posit that this strategy simultaneously affects information asymmetry and disclosure.FindingsFindings suggest that social disclosure and environmental disclosure substitute each other in reducing stock market asymmetry.Research limitations/implicationsThe measurement of social and environmental disclosure is based upon a coding instrument that makes some explicit assumptions about the value and relevance of information. Moreover, information asymmetry cannot be directly measured and is inferred from the behaviour of proxy variables such as share price volatility and bid‐ask spread.Practical implicationsResults suggest that social disclosure reinforces the informativeness of environmental disclosure for stock markets, even substituting for it under certain conditions. Stakeholders must assess and retain an increasing flow of information: a more efficient disclosure strategy becomes critical if firms want to convey the right picture of their CSR performance.Originality/valueTo the best of the authors' knowledge, this is the first study to explore the joint effect of social disclosure and environmental disclosure in reducing information asymmetry.