It was a bold move. In January, Bertolini told Aetna employees the company would boost its own minimum wage to $16 (as much as a 33% increase for some workers) in April and substantially upgrade health benefits for those at the bottom rungs of the company—something that would improve the lives of thousands. The CEO called it an “infrastructure investment in the quality of our employees,” saying it would not only help trim the $120 million that Aetna currently spends each year to rehire and retrain workers but also boost employee engagement with customers. Investors seem to understand the rationale. The insurer’s stock is up 22% since the Jan. 12 announcement, trouncing the S&P 500. And that may help explain why Wal-Mart, Target, and other big companies quickly followed suit.