Through empirical investigation of the Eurozone and Greek debt crisis 2010–12, this article demonstrates how a peak organization of financial firms—the Institute of International Finance —was able to mobilize its members transnationally to secure several key political and economic objectives. At the height of the crisis, large European banking firms were threatened by the prospect of a disorderly Greek default, coercive intervention by governments, and, potentially, a regional banking collapse. In this context, representatives from the IIF entered the policymaking process (...) to facilitate concerted private sector action, assisting EU officials with the negotiation of a substantial and orderly creditor writedown, and cooperating with legal action by the Greek government to sideline a minority of financial firms hostile to the deal. The article shows that the IIF’s disproportionate influence over policymaking was a result of their technical expertise, their ability to recruit individuals with long-standing experience of sovereign debt restructuring from the public and private sector, and the operation of elite revolving-door processes. In contrast to recent studies showing that financial actors are able to exercise more power at the national level by remaining collectively inactive, these findings suggest that, at the transnational level, financial actors can be most effective at securing their preferences when they are well organized and when they coordinate politically on the basis of collective interests. (shrink)