The new wave of mergers and acquisitions after the global financial crisis intensified the interest of policy makers and academics in bank concentration and competition and the role of the state in competition policies and regulations (policies and laws that affect the market structure and degree of competition). It is important to not only make sure that banking sector is competitive, transparent and efficient, but also stable. The purpose of the study was to investigate and analyze the degree of concentration in Estonian banking market and its impact on competition and market structure of financial markets over the period of 2013-2017. Both the structural and the non-structural measurement approaches of concentration and competition, along with the desk research, a case study and interviews with the financial sector professionals and an independent expert was employed to address research purpose. The findings of the study indicate that, in the Post-Soviet and nowadays EU member country – Estonia, high concentration coexist with the high and moderate competition levels and relationship between concentration and stability seems to be positive, meaning that high concentration results high stability of this banking market. The monopolistically competitive Baltic banking market is based on the contestable market equilibrium as banking sector is prone to the existence of high segmentation and product differentiation. Large banks with high share of foreign capital operate as universal banks, providing various services to the different market segments at very competitive rates, while smaller banks concentrate on a specific range of services. The Scandinavian-connected banking system of EU member Baltic country is modern and efficient, with best-regulation and high level of transparency in the region.Estonian financial markets are bank dominated, characterized with monopolistic banking structure, with leading roles of a few universal profile banking institutions, dominating not only banking sector, but whole financial market.