Introduction. The article presents the results of the integrated methodology for assessing stability developed by the author, tested at the branches of the Interregional Distribution Network Company of the Center and Volga Region, which differs from the already known methods in terms of characteristics, coefficients and structure. The main indicators of the electric grid company branches’ stability are identified, taking into account the industry priorities. An assessment of 9 branches’ stability was carried out, weaknesses and strengths of their activities were identified. Theoretical analysis. The main approaches to the concept of “company sustainability” are analyzed. Despite the abundance of definitions, common features that characterize a “sustainable enterprise” can be distinguished: positive performance, long-term solvency, successful opposition to external and internal influences, integrity of the enterprise as a system and the strength of internal and external relations, and all this in the long term prospects. Empirical analysis. The methodology for assessing the stability of an electric grid company branch involves the selection of the branch stability main indicators. As a result of evaluating the company’s performance using these indicators, it is advisable to propose an integrated indicator of assessing the stability of IDNCs. Results. As a result of evaluating the branches according to the method developed by the author, one can draw a number of conclusions about the situation, strengths and weaknesses of the branches, improve the management system of the electric power industry, thereby optimizing the use of resources necessary for the sustainable development of the company and the industry as a whole.