Facebook has spent billions of dollars on investments -- and it's just getting started

Justin Sullivan/Getty "We still think we're early in investing in the business." Those are the words of Facebook CFO Dave Wehner on the company's recent fourth-quarter earnings call. To his point, Facebook increased its spending significantly in 2015, up 55% on a non-GAAP basis for the year. At the same time, fourth-quarter operating margin increased to 60% last year, up from 58% in both 2013 and 2014. Despite its focus on investing for the long-term growth of the company, Facebook's 60% operati...