But there would probably be only a limited impact on capital because accounting rules give banks wide latitude in calculating the net presentvalue of the bonds, enabling them to reduce the hit they would take to capital.
First, by the corporate income tax, then again by the individual income tax through the tax on dividends, then if you sell the capital investment, through the capital gains tax (which taxes the increase in the presentvalue of the future income stream to the investment, which will be taxed again when earned), then when you die, by the death tax.