This paper studies the impact of the loan-to-deposit (LTD) ratio regulation – a specific macroprudential policy instrument introduced in Korea – on bank-level lending supply and the subsequent firm-level real consequences. The bank-firm-level matched loan data reveals that small and medium enterprises (SMEs) were particularly hit by adverse lending supply shocks from banks with higher pre-regulation LTD ratios. However, they were compensated by new loans extended by banks with lower pre-regulation LTD ratios as well as unregulated non-bank financial institutions (NBFIs). After all, the regulation did not result in adverse consequences on firm-level net credit or real performance, possibly at the cost of rising corporate loans extended by the shadow banking system.