The development of the construction industry leads to an increase in small businesses both in construction and in the sale of building materials. Besides, small business fills the market with various goods, solves various social and economic issues such as unemployment, industry monopoly. However, its activity can't exist without sufficient financial support. A two-level mathematical model of interaction between a retail enterprise and a commercial bank as a funding structure is considered. To research the proposed model, the method of simulation modeling based on numerical search was used. A computer program was created to build a Stackelberg equilibrium algorithm with hierarchical control as an impulsion. The algorithm can be used to find the optimal values of the control parameters of an individual entrepreneur and a commercial bank. These values maximize the objective functions and profit of the system participants. The identification of the proposed model was carried out on the basis of data obtained from the Internet. Finally, the results were obtained using numerical examples.A number of conclusions could be made about the functioning of the entire system.

Keywords: hierarchy,two-level system, credit, Stackelberg, small business, bank