Event-Time Effects of R&D Intensity and Green Financing Complementarities on Capital Costs, Valuation, and Green Innovation in S&P 500 Firms

This study tests whether labeled green and sustainability-linked financing complements firms’ R&D to lower the weighted average cost of capital (WACC), raise valuation, and shift innovation toward climate mitigation technologies. Using a 2012–2024 panel of S&P 500 constituents with complete coverage, this study applies a staggered-adoption difference-in-differences design with interaction-weighted event-time estimators and entropy balancing; WACC is decomposed into equity and debt components, valuation is measured by Tobin’s Q, and innovation outcomes cover patent counts and the CPC Y02 share, with matched-bond and secondary-market comparisons for the debt channel. Within two years of first-time adoption, this study observes a meaningful decline in WACC (approximately 40–60 bp) driven mainly by the cost of debt, alongside higher valuation and increased innovation intensity with a larger Y02 share. Effects are larger where R&D intensity is higher and are strongest for use-of-proceeds green bonds and for sustainability-linked contracts with material KPIs and non-trivial step-ups. These results indicate that labeled financing is most effective when aligned with credible R&D pipelines and verification mechanisms, clarifying its governance role in corporate sustainability strategies.