Managers are increasingly uncertain over the source (home nation or foreign nation) of antitrust holdup for domestic mergers with significant international implications. I propose a conceptual framework that predicts the source of antitrust holdup for domestic mergers. I find an industry's global competitiveness to be the primary driver behind holdup source. Further, I factor institutional conditions to yield more precise predictions tailored to the cross-national environment for antitrust policy. Exploratory empirical tests based on the merger policies of 27 antitrust jurisdictions over the 1992–2000 period provide support for baseline predictions. Finally, I generate prescriptive propositions that yield implications for effective political strategies. Copyright © 2005 John Wiley & Sons, Ltd.