<p>We examine how radical industry transformations shape firms’ internationalization, addressing the limited theorization of how industry-level dynamicsinfluence internationalization processes. Drawing on a historical case study of Telecom Finland’s internationalization during two radical transformations in the European telecommunications industry (1987–1998), we show how industry transformation simultaneously orients firms toward parallel internationalization and constrains its execution through systemic industry uncertainty, leading to two contributions. First, we offer an industry-driven explanation for why firms internationalize into multiple markets in parallel. Industry transformation enables parallel entries by creating simultaneous opportunities and actively orienting firms toward parallelism, as industry conditions shape what managers interpret as viable responses. Second, we expand understanding of uncertainty in internationalization processes by introducing the concept of systemic industry uncertainty, a form of transformation-driven uncertainty originating at the industry level, shared across actors, interdependent across markets, and irreducible within the relevant decision windows. Distinct from the market-specific uncertainty emphasized in internationalization process literature, systemic industry uncertainty impedes established uncertainty-reduction mechanisms—learning, network-based knowledge, and diversification—showing that uncertainty shapes internationalization in previously unrecognized ways. Our findings suggest that managers should closely follow industry-level developments, as these play a more central role in shaping internationalization than existing models assume.</p>