Abstract: Little is known about the bank-firm systemic risk from the perspective of the diversification of related businesses connections between banks and firms. To investigate the systemic risk of bank-firm system from the perspective of lending relationships with different loan terms and common asset holding relationships of different investment cycles, a multilayer network model is proposed. Based on the multilayer network model, the respective impact of multilayer network structures and the behaviors between banks and firms on the systemic risk is explored. The results are as follows. Regarding the multilayer network structures, the systemic risk under the combined impact of the multilayer network is significantly greater than the combined effect of any two-layer network, and the heterogeneities of multilayer network nodes has capability to resist the systemic risk. As for bank-firm subject behaviors, the longer loan term and the longer investment cycle increase the systemic risk to a certain extent, while the investment cycle is more sensitive. Decreasing the proportion of long-term investments and increasing the selection proportion of external assets can reduce the systemic risk, while the selection ratio of borrowing objects has little effect on the systemic risk relatively. The research of this paper is conducive to digging deep into the internal relationships among the multilayer network structures, the bank-firm subject behaviors and the systemic risk from a theoretical level. The above research results have certain theoretical reference value and practical guidance significance for the supervisory authorities to prevent the systemic risk and maintain the stability of the financial market.

Key words: multilayer network model; bank-firm systemic risk; multilayer network structures; bank-firm subject behaviors