Beyond markets and hierarchies: Williamson's legacy and the frontiers of institutional analysis

More than fifteen years after Oliver E. Williamson's 2009 Nobel Prize, this article takes stock of transaction cost economics and maps its future. Drawing on a bibliometric analysis of 67,841 papers citing Williamson's work between 1975 and 2025, we document a research programme that is neither exhausted nor unchanged: the share of citing papers that engage substantively with the framework (deploying core transaction-cost concepts rather than citing Williamson in passing) has fluctuated within a narrow band of three to five per cent for three decades, yet its conceptual centre of gravity has migrated from vertical integration and hierarchies toward outsourcing and hybrid governance, and its geography has shifted beyond the North-American founding generation. Building on this evidence, we propose two research agendas for the next fifteen years: a dynamic reformulation of the framework, in which governance transitions and transaction costs themselves become objects of strategic design, and an extension to the frontiers where these dynamics are most acute, from decarbonisation infrastructure and outcome-based contracting to geopolitical fragmentation and contract automation.The six contributions gathered in this special issue put this agenda to work, combining a reassessment of Williamson's conceptual legacy with applications to contemporary governance problems in environmental regulation, procurement, local public services, bidding markets, and municipal finance.