Sustainable Investing: The Role of Green Bonds in Portfolio Performance

Abstract

This paper explores how green bonds can be used to improve portfolio performance using the mixed-method design, which combines quantitative econometric modeling and qualitative data analysis of the perceptions of investors. The research builds diversified portfolios with data on global green bond indices, traditional bond indices, equity indices, and macroeconomic factors in determining the relationship between risk and returns of sustainable investments. The descriptive statistics and correlation matrices indicate that the green bonds have moderate relations with equities and traditional bonds, which implies that the bonds have high benefits of diversification. The regression analyses support that green bond allocations have a positive and statistically significant effect on the portfolio returns even when macroeconomic shocks like interest rate fluctuations and inflation are considered. Mean-variance-based optimal portfolio optimization shows that the addition of green bonds always shifts the efficient frontier outward, which enhances the overall portfolio efficiency, particularly in times of volatility like the COVID-19 crisis.Risk-adjusted performance indicators, especially, Sharpe Ratios and Conditional Value at Risk (CVaR), reveal that the green-bond portfolio always outperforms traditional counterparts, particularly in the volatile environment. Robustness checks further validate these findings across different sub-periods. The qualitative review also presents increased investor confidence in sustainable fixed-income instruments, but worries about greenwashing and transparency remain. All the results highlight the point that the green bonds offer not only better financial performance but also substantial additions to the environmental goals, which supports the idea that they may serve two purposes: promoting the portfolio resilience agenda and the global sustainability agenda.