We study how lenders respond to excessive optimism in the corporate sector. Our identification relies on plausibly exogenous variation in optimism across areas in Italy. We document that firms in optimistic areas hold favorable views about their own business, and that they are more likely to default on their debt. Banks are more likely to deny credit to firms in optimistic areas, but only for loans that cannot be easily collateralized. Our findings provide empirical support for the theoretical prediction that banks' collateral provision reduces the efficiency of the credit market when the corporate sector is prone to excessive optimism.
