The year 1720 witnessed the world’s first international financial crisis. Instead of retelling the standard narrative that focuses on John Law and his System, this chapter uses the records of the stock speculator James Brydges during the Mississippi and South Sea Bubbles to illustrate the different capacity for impunity in the 1720 crisis. Changes in impunity were due to the expansion in the complexity of finance, and the fraught process of trying to establish central banks as the main institutional form of immune actors in that new complex financial world. The financial bubbles of 1720 were connected by flows of capital, information, and personnel, which were beyond the capacity of either the French or the British government to regulate. For the first time, financial instruments and techniques existed, which were beyond the understanding of the educated amateur and were powerful enough to provoke wide-ranging economic disorder.