We measure the impact of bank capital requirements on corporate borrowing and business activity. We use loan-level data and take advantage of the transition from Basel 1 to Basel 2. While under Basel 1 the capital charge was the same for all firms, under Basel 2, it depends in a predictable way on both the bank's model and the firm's risk. We exploit this two-way variation to empirically estimate the semi-elasticity of bank lending to capital requirement. This rich identification allows us to control for firm-level credit demand shocks and bank-level credit supply shocks. We find very large effects of capital requirements on bank lending: a one percentage point increase in capital requirements leads to a reduction in lending by approximately 10%. At the firm level, borrowing is reduced, as well as total assets (mostly working capital); we provide some evidence of the impact on employment and investment. Overall, however, because Basel 2 reduced the capital requirements for the average firm, our results suggest that the transition to Basel 2 supported firm activity during the crisis period.
