We provide the first evidence that conflicts of interest arising from commercial ties lead to bias in environmental, social, and governance (ESG) ratings. Using the acquisitions of Vigeo Eiris and RobecoSAM by Moody's and S&P as shocks to the commercial ties between ESG rating agencies and their rated firms, we show that, after their acquisitions by the credit rating agencies (CRAs), ESG rating agencies issue higher ratings to existing paying clients of the CRAs. This effect is greater for firms that have more intensive business relationships with the CRAs, but weaker for firms with more transparent ESG disclosures or higher long‐term institutional ownership. The upwardly biased ESG ratings help client firms issue more green bonds and enable the CRAs to maintain credit rating business. Finally, the upwardly biased ESG ratings are less informative of future ESG news. Overall, the business incentives of rating providers appear to engender ESG rating bias.

We examine how common institutional investors (CIIs) facilitate the financial reporting comparability (FRC) of US firms. Common ownership increases FRC of firms that are directly owned by CIIs (via a direct effect) and has positive spillover effects on other firms in the same industry. We find spillover effects in two types of firms: (1) those that are commonly owned by different institutional investors but are connected through common firms, and (2) those that do not have any common ownership. These results suggest that the effect of common ownership goes beyond commonly owned firms and extends to non‐commonly owned firms. Furthermore, we find two mechanisms for the direct and spillover effects of common ownership on reporting comparability: firms' hiring of common auditors and their adoption of similar accounting practices. Overall, we provide comprehensive evidence on how common institutional ownership benefits the comparability of financial reporting in the United States.