‒  The Banking Union and in particular its Balance Sheet Assessment, provided that it is seen as credible, will increase transparency and thus reduce the uncertainty attached to the market value of banks. ‒  Pricing will more correctly reflect the true value of the banks. The discount unfairly attached to good banks will be reduced, or even eliminated.
The weak banks will, however, most probably see their share price drop even further. Banks that are no longer deemed viable need to be restructured or wound down through orderly resolution processes. ‒  An unanswered question still is the potential impact on the required return on equity.