Within the US banking system, all of that is, for the most part, kept in line with the Federal Reserve System and other regulatory apparatuses to keep everybody

Within the US banking system, all of that is, for the most part, kept in line with the Federal Reserve System and other regulatory apparatuses to keep everybody honest. Outside of the US, you run into so-called "eurodollars" (unrelated to the Euro currency) which is a complete mess of intertwined financial systems from across the planet that a lot of people smarter than me pin on being the cause of the European debt crisis.