On 31 July 2024, the European Securities and Markets Authority (ESMA) issued an opinion that is addressed primarily to Member State competent authorities (NCAs) which tackles regulatory and supervisory arbitrage risks stemming from specific business set ups whereby Multifunction Crypto-asset Intermediaries (MCIs) would only seek authorisation under the Markets in Crypto-assets Regulation (MiCAR) for brokerage services but intend to leave a large part of the group activities (and in particular the operation of a trading platform for crypto-assets) outside of MiCAR. The purpose of the opinion is to share relevant criteria to promote supervisory convergence and support the NCAs’ assessment of the business model and activities that the applicant MCIs intend to carry out, as well as the ongoing assessment of how such activities are carried out. The opinion calls for a case-by-case assessment, outlining the specific requirements that should be met regarding best execution, conflicts of interest, the obligation to act honestly, fairly and professionally in the best interests of clients and the obligation relating to the custody and administration of crypto-assets on behalf of clients.