The economist Gabriel Zucman came up with an ingenious way to estimate the wealth hidden in the offshore banking system. In theory, if you add up the assets and liabilities reported by every global financial center, the books should balance—but they don’t. Each individual center tends to report more liabilities than assets. Zucman crunched the numbers and found that globally, total liabilities were 8 percent higher than total assets. That suggests at least 8 percent of the world’s wealth is illegally unreported.
