We examine how banks' capital requirements affect the way bank mergers are financed, as well as the stock-market reaction to the merger announcement. We find that the capital position of the acquirer is one of the two factors most strongly influencing the choice of financing method; the other is the relative size of the merging banks. The smaller the acquirer in relation to the target bank and the higher the acquirer's capital adequacy ratio, the more likely it is that the acquisition will be financed by a stock swap. The capital requirements also affect the market reaction, through their effect on the financing method choice. The value of the acquirer's equity decreases more at the time of the merger announcement if the method of payment is stock. Like prior studies, we find that the abnormal return on the target banks' stock is positive. Copyright Blackwell Publishers Ltd 1997.