The commercial sector of the economy is the guarantor of the stability of the state functioning, since the economic subjects employed in it are able to combine personal (entrepreneurial) interests with the interests of the population, thanks to their economic potential formed at the expense of business processes aimed at profit (the main source of financing measures to meet human needs for the existing benefits). The purpose of the study - the formation of accounting and management tools that allow corporations to conduct a comprehensive analysis of the effectiveness of financial relationships, taking into account all the conditions of activity inherent in big business. In the course of the study the calculative-constructive, deductive and inductive methods were used, which allow to interconnect dialectically resultant and factor efficiency indicators, in our case, in the sphere of corporate finance, through multiple-additive correlation of efficiency and cost of financial relations in big business. The article presents the system of indicators developed by the authors, offered to corporations for assessment by the accounting and management apparatus of efficiency of their financial relations, which play the key role in business due to the greatest liquidity of monetary resources. The toolkit of such a system is built on the study of controlled and uncontrolled conditions of corporations' functioning. The use by corporations of the recommended author's approach will provide them with the optimization of the result and costs (profit and expenses) and, accordingly, the effectiveness and cost effectiveness (direct and indirect profitability or profitability) of activities, by which their financial efficiency is determined.