This paper shows that industry specialization of loan officers facilitates monitoring synergies and lowers credit default rates of small- and medium-sized enterprises. We exploit a wave of early loan officer retirements as a quasi-natural experiment, in which the resulting borrower reallocations changed the industry specialization levels of the remaining loan officers. In a difference-in-differences analysis excluding all reallocated borrowers, we find that a negative shock to loan officer specialization increases default rates due to an inferior production of default risk information and excessive loan growth. A positive shock to loan officer specialization generates opposite effects. Our results suggest that loan officers can exploit industry specialization and related monitoring synergies to improve lending decisions and thereby contribute to lowering credit default rates in the bank's borrower portfolio.

本文表明，信贷员的行业专业化有利于监控协同效应并降低中小企业的信贷违约率。我们利用信贷员提前退休的浪潮作为准自然实验，由此产生的借款人重新分配改变了剩余信贷员的行业专业化水平。在排除所有重新分配借款人的双重差分分析中，我们发现，由于违约风险信息的生成质量较差和贷款增长过度，信贷员专业化的负面冲击会增加违约率。对信贷员专业化的积极冲击会产生相反的效果。我们的研究结果表明，信贷员可以利用行业专业化和相关监控协同效应来改善贷款决策，从而有助于降低银行借款人组合中的信用违约率。