Аннотация:A model examines a firm’s optimal behavior in a financial market under full information. It makes it possible to specify and modify the efficiency criterion structure of investment projects implemented by the firm, the traditional definition of discount rate, and rule of estimating of investment project financial feasibility. From the built model is derived that in the general case, the discount rate determined as the rate of money valuations decrease in the optimal plan is time-variant and depends not only on market situation but also on the firm’s financial position. It is found that the efficiency criterion of investment projects implemented by the firm, which is adequate to the firm’s interests differs from the net profit value (NPV) criterion. In addition to discounted sum of the project’s cash flows, one must take into account also the market value of assets created under the project, which facilitates raising loans.