Information contagion and bank herding

We show that the likelihood of information contagion induces profit-maximizing bank owners to herd with other banks. When bank loan returns have a common systematic factor, the cost of borrowing for a bank increases when there is adverse news on other banks since such news conveys adverse information about the common factor. The increase in a bank's cost of borrowing relative to the situation of good news about other banks is greater when bank loan returns have less commonality (in addition to the systematic risk factor). Hence, banks herd and undertake correlated investments so as to minimize the impact of such information contagion on the expected cost of borrowing. Competitive effects such as superior margins from lending in different industries mitigate herding incentives.