In this paper, we investigate whether investors are willing to pay a higher price to invest in social projects, a differential that we call socialium. Using a nearest neighbor matching procedure on various samples of social and conventional bonds issued between September 2015 and 2020, by public or transnational organisations, we find that, on average, there is no yield and spread differential neither on the primary nor on the secondary market. The result holds even after taking into account the impact on market liquidity or shocks linked to political and economic uncertainty, likely to address silent issues of social risks. The empirical results on the size of socialium, which are not statistically significant, provide us with a rare opportunity to bridge two streams of reasoning stemming from the financial and sociological approaches. We explain why the issuers and investors still bear an interest for the social bonds through the lens of new institutionalism. This theory explains how the social influences, institutional and mimetic pressures and the acquisition of legitimacy in the eyes of society and stakeholders influence the issuance and the acceptance of social bonds.