[Zope] Zope in transactional web sites

Hi Apologies if this list is the wrong place to post this request. I am looking for examples of cases where Zope or Plone have been used as the basis for transactional web sites - e.g. banking, shopping. Specifically, Zope should provide the front end to a transactional back-end, preferably processing medium to high volumes of transactions (5 - 10 million/year). I have searched all the Zope related web sites I know but all the case studies provided deal with informational rather than transactional sites. Any pointers appreciated awillo