Reducing the risks in the financial markets and supporting financial stability are the main priorities of financial markets’ regulation. To increase the security of transactions when trading with financial assets, it is essential to reliably identify the market participants. Following the initiative of the G-20 summit in 2012, there has been an unprecedented attempt to design a universal tool – a global legal entity identifier within the LEI system. The article deals with theoretical resources of the “legal entities” concept, obstacles preventing the identification of the financial market participants and the characteristic of the project of the universal identifier of entities entering financial markets’ system. The article also contains an evaluation of the current state of the LEI system construction and an analysis of conditions for its completion.