Large-scale agile transformation implies that agile approaches are moving from standalone in-formation system development units such as teams towards being applied in more complex organi-sational settings with multiple and diverse units. Research on large-scale agile transformation suggests that agile methods with its focus on mutual adjustment increases interdependencies be-tween diverse units. However, extant empirical research on how interdependencies can be man-aged in large-scale agile transformations is scarce. We report from an interpretative case study of an agile transformation initiative in a company with 20.000 employees. Based on data from 32 interviews combined with participatory observation in retrospectives we analyse how “collabora-tion rooms” are used to manage the interdependence between heterogeneous units, and how the collaboration rooms are conceived by information systems development practitioners as an agile transformation initiative. Using the concept of trading zones we contribute by discussing how het-erogeneous units can manage interdependencies by using collaboration rooms as a minimum via-ble common ground. We discuss how the minimum viable ground i) fit new practices with existing practices, ii) allows flatter decision structures, and iii) is a subtle and iterative approach to organ-izational transformation.