In this article we explore the emergence and evolution of collaboration agreements among different types of intermediaries in the UK and Mexican financial systems. Collaboration in the UK looks at agreements between non-bank and non-finance providers aiming to modify their competitive capabilities and circumvent barriers to enter deposit markets. Collaboration in Mexican banking considered agreements between commercial banks and small regional banks during the period of 1945 to 1975. Agreements in Mexican banking are benchmarked against collaboration in the UK. As a result, research in this article sheds light on the success of collaboration agreements through changes in competitive strength rather than the longevity of the transaction or the formality and structural visibility of the agreements. Evidence documented here also helps in remedying a shortage of research around financial institutions in less developed countries and the economic and business history of Latin America, while providing an international comparison.