This chapter discusses payment settlements in the post-Bretton-Woods-System financial market and their impact on emerging economies. It analyses Mexico’s financial openness and its insertion into the international economy. The end of dollar-gold convertibility led to mayor institutional changes in the financial system that modified the perception of money in the economy, giving way to the creation of an international monetary system driven by private debt. Emerging countries’ position in the international financial system continued to be highly dependent on external finance even though some countries’ local currencies became internationalised. The chapter also discusses the characteristics of the economic opening through the Mexican economy’s external account. Financial variables became dominant in developing countries, particularly in Latin America, based on an export-driven accumulation model. The chapter reviews Mexican peso-foreign exchange (FOREX), highlighting the impact on financial stability. One final piece of information that indicates the instability generated by the liquidity of the FOREX market is the small size of Mexico’s financial centre.