World Bank pandemic bonds paid out only after death tolls passed a threshold. They’re part of a booming market where investors turn calamity into capital.Adobe Stock/MITP ReaderThe pandemic bonds — a financial device made up by one of the world’s most powerful institutions, the World Bank — can seem like a great idea for raising money to fight pandemics. Money is pooled ahead of time, rather than waiting for governments to pony up monies to stop a deadly infectious disease after it spreads. Priv...