The purpose of the research is to determine the optimal structure for financing the investment activities of industrial enterprises in the context of ensuring the economic security of such activities. In addition, the use of minimax strategies was substantiated in the direct selection of funding sources and the adoption of appropriate strategic decisions to minimize potential losses. Methodological approaches of strategic management for specifying the strategic guidelines for ensuring the economic security of the investment activities of an industrial enterprise were used to achieve the purpose. Optimization models have been developed on the basis of empirical studies at Ukrainian industrial enterprises and the survey conducted. The developed model for optimizing economic security based on minimizing losses in the formation of sources of financing investment activity allows enterprise management to make weighted strategic decisions and provides sufficient arguments for measures in the field of economic security.