We study the effect of a merger between two large banks on credit market competition. We identify the competitive effect of the merger using matched loan-level and firm-level data and exploiting variation in the merging banks’ market overlap across local lending markets. On the credit market side, we find a reduction in lending, in particular through termination of relationships. In the average market, bank credit decreases by 2.7%. On the real side, firm exit increases by 4%, whereas firms that do not exit and firms that start up experience no adverse real effect on investment and employment.