The New York Stock Exchange, the beating heart of global finance, is owned by a single company. But what began as a secretive club of 24 brokers under a tree in 1792 has evolved into a $100 billion corporate empire. In the early days of America, New York’s markets were chaotic and corrupt. To bring order, a small circle of merchants and bankers signed the Buttonwood Agreement, pledging to trade only with each other and set fixed commissions. Their pact created the first centralized and trusted f