the job that paid 450% interest—and ruined economies

Medieval monarchs had a problem: they needed cash immediately to fund wars, but tax collection was slow, unreliable, and months away. Enter the Italian merchant bankers, who created what was essentially the first high-stakes lending market.

These weren't your neighborhood money lenders. Families like the Medici, Bardi, and Peruzzi ran sophisticated international operations, moving gold across borders and extending credit to kings who had armies but no liquidity. The catch? Interest rates that would make a payday lender blush. Rates of 120% annually weren't unusual, and some loans carried effective rates even higher when you factored in the various fees, currency exchanges, and "gifts" required to secure the deal.

The business model was brilliant until it wasn't. When Edward III of England defaulted on his war loans in 1345, he took down the two largest Italian banks of the era—the Bardi and Peruzzi—triggering a financial crisis that rippled across Europe. The Bardi alone had lent Edward the equivalent of twice Florence's annual tax revenue.

Why did monarchs accept such brutal terms? Because the alternative was losing wars, territories, and thrones. The bankers knew this, and priced accordingly. They were running the world's first sovereign debt market, and the returns—when kings actually paid—could fund entire family dynasties. Of course, the risk was that your biggest client might simply declare your debt void, which is exactly what happened often enough to keep things interesting.