¿En qué medida la emisión de bonos verdes por las empresas del S&P 500 mejora su desempeño ambiental?

Abstract

In response to climate challenges, green bonds have emerged as a key instrument for financing environmentally sustainable projects. Yet, their actual environmental impact remains contested. This study evaluates the effect of green bond issuance on environmental performance among S&P 500 firms between 2013 and 2024, focusing on changes in carbon intensity and Environmental Pillar Scores. Drawing on Legitimacy Theory and Corporate Social Responsibility (CSR) Theory, the research examines whether green bonds yield substantive environmental improvements or serve primarily as reputational tools. Using panel data from Refinitiv Eikon, the analysis applies a matched difference-in-differences (DiD) methodology, comparing issuers to non-issuers matched by sector and year. Dynamic event-time models and forecasting are used to assess short- and medium-term effects. The results show no statistically significant average reduction in carbon intensity immediately after issuance. However, by year three, a significant decline is observed, suggesting that green bonds may support long-term emissions reductions. In contrast, no significant improvements are found in Environmental Pillar Scores, raising concerns about their value as indicators of environmental progress. The findings suggest that green bonds may facilitate decarbonization over time, but their effectiveness is highly context-dependent. Sectoral characteristics, firm-specific factors, and implementation quality all shape outcomes. These results underscore the importance of aligning reputational signals with measurable environmental impact and call for stronger verification standards in green finance. This study contributes firm-level causal evidence to the sustainable finance literature and highlights the need for greater accountability in the green bond market.