It’s unusual for a CEO who has led a company through more than ten years of strong growth and financial performance to stop and consider whether the business should be run differently to meet future challenges. It’s even more unusual for such a chief executive to initiate a major transformation introducing a new way of managing this highly successful company—a transformation involving its culture, organizational structure, decision-making processes, and leadership style.

Yet this is precisely what Roberto Setubal, the CEO of Brazil’s Itaú Unibanco, launched in 2005. By then, decades of steady organic growth and well-chosen acquisitions had made the company, founded in 1945 and controlled by the Villela and Setubal families, Brazil’s second-largest private-sector bank and one of Latin America’s most profitable institutions.

In November 2008, midway into the change effort, Banco Itaú and a domestic competitor, Unibanco Holdings, agreed to a merger forming one of the world’s top 20 banks by market capitalization. Setubal, named CEO of Itaú Unibanco Holdings, here speaks to McKinsey director Frederico Oliveira about Itaú Unibanco’s journey from a command-and-control management model to an open and creative dialogue, and what the merger will mean for this journey.