The internet has given rise to anti-brand communities which are forming around common aversions toward brands. We illuminate this phenomenon in the context of social networking sites and consider effects on sponsorships of the opposed brand. Therefore, we conduct a mixed method study of facebook-organized anti-brand communities using the brand FC Bayern Muenchen and its main sponsor Deutsche Telekom. our findings reveal that community membership negatively influences both attitude and purchase intention toward the sponsor of the antibrand. Consequently, we establish the relevance of antibrand communities for both the brand and their sponsors and derive marketing implications.