Nothing terminal. Some of this is a change in the way the rating companies are doing math and not a change in the condition of the banks.
Most bank stocks are swirling the bowl already, so I don't think they'll be punished by the professional investors.
Those stocks have been swirling the bowl since 2008. In the aftermath, several played with some fancy accounting tricks (reverse splits) to make their stock appear more worthwhile. The big problem is that traders an investors seem to have short memories, and are bound to repeat the same mistakes. Watch for the "dead-cat-bounce".