Mexican telecommunications magnate Carlos Slim trimmed his holdings in the New York Times Co., selling roughly half of his investment this month at a price of just about $240 million. With the stock up enormously over the last year, the sell-off means a massive windfall for Slim — already one of the richest people on Earth. The news was first reported by Bloomberg, which noted a relatively unremarkable public release from Slim’s company earlier this month. Slim first became an investor in the Times in 2009, when he loaned the company $250 million to help get it past the financial crisis. He...