A massive leak of documents from HSBC’s Swiss banking arm has revealed an array of sketchy dealings with wealthy individuals, including dictators and arms traffickers, through which the bank helped unsavory characters dodge taxes and avoid government scrutiny. Among the unsavory characters exposed in the leak are a number of prominent donors to the Clinton Foundation. For example, the leaked documents detailed a five million Swiss franc cash transaction to British business mogul Richard Caring: HSBC staff explained handing Caring the huge sum of cash by quoting a statement by him that he planned to deposit the cash with another...