The importance of observing the entirety of the financial observations of the functioning of the system can be observed through several phases in the real functioning of the banking system. In the paper, it was observed from the macro level, in terms of the organization of the banking system in the processes of the real functioning of the financial system in one country, for example the Republic of Serbia. In addition, it should be observed from a practical aspect in the functioning of the banking system, which can be observed in the context of a real process, and through the observation of a possible merger and acquisition, it can be presented in the following three phases: the phase of strategic preparation, the phase of negotiation and research, and the phase of finalization and integration in banks that have joined the given business activities.