… if you follow the flow of money around the world, you might be surprised to find that the central node of global finance, the place where money passes through most often, is London, not New York. Wall Street, of course, is no piker. American investment banks — partly because the U.S. economy is the largest in the world — do more business and make more money. But when it comes to international transactions, London is the world’s financial center. The City of London, its Wall Street, employs more than 300,000 people, whereas Wall Street itself employs fewer than 200,000. Banks in the United States hold total assets that come to about 85 percent of the country’s gross domestic product. In Britain, the banks hold almost 400 percent more money than its G.D.P., mainly because so much international business takes place there. And as the U.S. share of global finance shrinks, international business matters more.