A billionaire couple is pumping money into the drug pricing debate. Can they loosen pharma’s grip?

John Arnold is legendary for turning contrarian bets into heaps of money. The soft-spoken Texan was a whiz kid trader at Enron before its fall. He then ran his own hedge fund, specializing in energy trading. Before he turned 34, he was a billionaire. He can afford his prescription drugs. But Arnold, now a philanthropist with…