Bankruptcy Propagation on a Customer-supplier Network: An empirical analysis in Japan

連鎖倒産という現象は、企業の取引ネットワークを通じての負のショックの波及という点でネットワーク特有の現象である。本論文では、販売先企業が倒産したことによる仕入先企業の倒産確率の上昇を、日本の100万社を超える企業情報、倒産記録、仕入先・販売先ネットワークから成るデータを用いて分析した。その結果、販売先の倒産は仕入先の倒産確率に有意に上昇させていること、例えば50%の販売先が倒産した場合、仕入先企業の倒産確率は元の値から約2倍上昇することが分かった。この結果を用いて、販売先の倒産の影響がマクロレベルでどの程度重要かを検証し、また連鎖倒産を阻止するための政府の政策（セーフティーネット保証）についても分析した。企業レベルでは販売先の倒産は倒産確率の重要な要素である一方で、生産ネットワークの構造（スモール・ワールド性）によって、1次から2次、3次の仕入れ先というように倒産が伝播する可能性は極めて低いということが分かった。

Since firms are interrelated via customer-supplier relationships, the bankruptcy of a firm may lead to the bankruptcy of its suppliers. Due to this contagion effect, one bankruptcy may trigger many subsequent bankruptcies of direct and indirect and have a nonnegligible impact on an aggregate economy. This paper empirically analyzes this bankruptcy propagation on a customer-supplier network by using a comprehensive dataset consisting of more than one million firms and their customer-supplier relationships, and bankruptcy records over April 2013 to February 2017 in Japan. We find that the contagion effect is significant at the firm-level; for example, if 50% customers of a firm go bankrupt, the firm's bankruptcy probability approximately triples. However, it does not immediately imply that there is a substantial risk at the aggregate level that a nonnegligible fraction of firms are forced into bankruptcies by the contagion effect. In fact, by simulating our model, we find that the reach of bankruptcy propagation is very limited in most cases and it is highly unlikely that bankruptcy spread extensively on the network. This is because of the structure of the customer-supplier network. The network structure contributes to absorbing bankruptcy shocks by an aggregate economy rather than spreads bankruptcy on the network.