The cyclical nature of the economic activity marked by the sudden breakdown of the expanding trends of the banking industry, has reflected on the erosion of the quality of the banks' capital structure as a guarantor of solvency in the necessity of public confidence. The need to establish new equilibrium relations in the post-crisis period, above all by upgrading the regulatory framework through the Basel III Standard, has determined the purpose of this research in questioning the impact of new capital requirements on the banking firm activities as a whole. A sample of research structured with the data of the 35 largest banking groups operating on the single European financial market, offers enough elements to establish a quality methodological framework for the synthesis in monitoring the impact of regulatory capital requirements on the volume and credit activity of banks. The results of the research undoubtedly led to the conclusion that in the inability to increase the absolute amount of equity to meet new capital requirements due to materialization of the risk and loss of market value of the banking firm, management structures slow down the growth of assets and reduce credit activity as the dominant source of endogenous money and additional credit potential. The overall reactive attitude towards economic flows, the banking industry establishes procyclical action through financial leverage and the change of business model, with negative impacts on the economy as a whole, particularly in bank-centric systems. Finally, the doctoral dissertation provided evidence about the posibilities of use dynamic panel models in the behavioral analysis of the banking firms after announcing and implementing new regulatory capital requirements and confirming the impact of new regulatory capital requirements on the growth and risk structure of banking assets. Internalization of losses in the now-changed conflict of interests "banking shareholderstaxpayers" could contribute to the re-afirmation of traditional credit-deposit financial intermediation with lower banking assets growth and moderate cyclical economic activity. We may conclude once again as many recent studies have confirmed so far, only a healthy and optimally regulated banking system can ensure an efficient allocation of social accumulation in the function of economic growth and development.