Both the EU and US markets are witnessing the progress of consolidation day by day. The gradual integration of banking organisations is one of the by-products of globalisation and liberalisation of international financial markets. Banks are a specific group of economic agents, whose creation and operation evades the terms and principles of classical economics. Every bank tries to generate, but not necessarily maximise profit, especially if this should happen at the expense of its stakeholders. Besides, the advent and growth of the theory of transaction costs, the agency theory and the theory of finance has changed the way economists perceive the role of consolidation in banking. Transaction costs theory assumes that banks will expand until the cost of carrying out additional operations internally becomes equal to the cost of conducting them in the financial market. On the other hand, consolidating banking transactions of at least two banks under the umbrella of one organisation and one management team increases efficiency, in line with the managerial theory. Shareholders expect the value of their investment to rise, which can be achieved through increasing revenue and through scale advantages resulting in reduced costs and higher margins. Additionally, mergers allow the banks involved to increase their profits if their activities previously overlapped, as the prices can now be set higher. The above considerations relating to theory show that consolidation in the banking sector - initiated due to cost pressures, the need to spread risk and diversify scope and field of activity, and finally by information asymmetry - is in fact a stage in an evolution from specialised bank organisations towards a universal system.