Eversana, a company that helps drugmakers sell their medicines, has acquired a smaller firm called Waltz Health that helps employers and health insurance companies purchase cheaper drugs, in a bid to build an alternative to traditional pharmacy benefits middlemen in the US.The combined company, which will remain closely held, is valued at $6 billion, according to Mark Thierer, who will lead it, though he declined to say what Eversana paid for Waltz....