In the context of the first Paris Agreement's global stocktake, transnational regulatory climate initiatives hold the potential to catalyse states' action and boost the process' transparency. However, transnational initiatives' own transparency has been questioned. This article investigates the transparency of 56 initiatives by focusing on the ‘quantity’ and ‘quality’ of the information disclosed. The analysis underscores limits pertaining to both elements. To explain variation, the article correlates transparency with the initiatives' type of actors, type of regulatory activity, number of functions performed and size and identifies what constellations of factors better explain transparency and lack thereof via a Qualitative Comparative Analysis. Large initiatives which involve public actors and perform multiple functions are more strongly linked with transparency. Other factors do not yield significant effects. By identifying areas for improvement in regulatory initiatives' transparency, the article contributes to a better understanding of their role in the stocktake process.