Are clean energy assets a safe haven for international equity markets?

While clean energy assets have become new investment vehicles for market participants, their potential for diversification of traditional investments has not been fully explored in previous studies. To fill this void, this paper investigates whether diversifying into clean energy stocks or green bonds could reduce portfolio downside risk for investors holding dirty energy stocks or international equity indices. Specifically, the risks of equity portfolios are compared before and after they are blended with clean energy assets. The incremental impact on the portfolio risk profile is evaluated through variable weightings for clean energy assets. The persistence of diversification effects is then explored by changing the assessment period. Results show that both green bonds and clean energy stocks provide risk diversification benefits for investors with dirty energy stocks. However, green bonds reduce risk while clean energy stocks generally increase the risk of the international equity index portfolio. Further analysis indicates the robustness of the results for the recent COVID-19 period. The findings broaden the limited understanding of the risk reduction capacity of clean energy assets to conventional equities and provide useful implications for investors seeking to decarbonize their equities and portfolio managers designing optimal portfolios to hedge against downside risks.