Abstract: The global economic crisis and the socio-economic consequences of the COVID-19 pandemic have a significant impact on the increase in volatility and risks of manipulation of stock asset quotes. The subject of the study is the organization of management of the investment fund process, taking into account non-market mechanisms for manipulating the value of shares of issuing companies. The purpose of the article is to improve the efficiency of managing the stock process based on the stock market model and procedures for fuzzy valuation of the value of shares of issuing companies within this model. The research methodology is based on the application of methods for analyzing economic phenomena and processes, a systematic approach to studying the development of issuing companies and stock markets. Modeling of fund processes is based on fuzzy logic theory and efficiency theory. The principles of stock market idealization and the principles of stock market management in a manipulated information environment are formulated. A model of the stock market is presented, which includes: an ideal model of the stock market, a model of fundamental disturbing factors and a model of stock market manipulation. Within the framework of the stock market model, an economic and mathematical model for estimating the value of shares of issuing companies has been developed, in which the uncertainty of parameters is described by fuzzy numbers. The novelty of the research lies in the formulated concept of factor psychodynamics (including a list of factors, functions of factors, the strength of factors and inertia of factors), which serves as the basis for the stock market model; as well as in the developed methodology for fuzzy valuation of shares of issuing companies. Participants of the stock market, potential investors, owners and acquirers of companies on the basis of the presented model of the stock market have the opportunity to obtain additional information about ongoing stock processes. Fuzzy procedures for estimating the value of shares of issuer companies make it possible to calculate the value of their shares in accordance with various forecast scenarios for the development of companies.