Was Covid-19 a wake-up call on climate risks? Evidence from the greenium

Building on the work by Liberati and Marinelli (2021), this paper presents a study on the greenium, i.e. the negative yield difference between green bonds and their conventional counterparts. We use a security-by-security data set comprising a large sample of green bonds exchanged on the main global security markets, integrated with the microdata employed in official statistics on security holdings and prices. After showing the existence of the greenium, we employ a twofold approach in order to contribute to the literature on this topic. Firstly, we exploit an econometric strategy based on security-level panel regressions and we find strong evidence for the existence of the greenium and for its increase following the Covid-19 shock; nonetheless, after the end of the state of emergency, we find evidence of a rebound of the greenium of different intensities depending on the issuing sector. Finally, we provide econometric evidence for a persistent excess demand in the green bond secondary market through a non-Walrasian disequilibrium model a la Maddala and Nelson (1974).