In its final quarterly earnings report of 2014, Facebook announced that it had recorded $701 million in profits—an increase of about 33 percent over the same period last year.

In its filing with the Securities and Exchange Commission (SEC), the company said that its fourth quarter advertising revenue hit $3.59 billion, an increase of 53 percent. Better yet, mobile advertising revenue comprised 69 percent of Facebook’s total ad revenue.

When Facebook went public in 2012, there had been some questions as to whether the company could adequately monetize mobile users. But those concerns seem to have largely been put to rest.

Many investors got spooked, lowering revenue estimates earlier this spring, after seeing Facebook’s Amendement to its S-1 filing, where Facebook said: "Growth in use of Facebook through our mobile products, where our ability to monetize is unproven, as a substitute for use on personal computers may negatively affect our revenue and financial results."

In June 2012, Facebook began its first ad campaign on mobile devices, with "Sponsored Stories" hitting handsets across the world. The company reported that at just three months earlier there were 901 million monthly active users, with over half of those being mobile users, and 80 percent of those outside the United States and Canada.

Now, as of December 2014, there are 1.3 billion monthly active users, a 13 percent year-over-year increase, which includes 745 million mobile daily active users, a 34 percent year-over-year rise.

In September 2014, the company wrote in another SEC filing: “We had 1.12 billion mobile monthly active users (MAUs) in September 2014. While most of our mobile users also access Facebook through personal computers, we anticipate that growth in mobile users will continue to be the driver of our growth for the foreseeable future and that usage through personal computers will continue to decline worldwide, including in key markets such as the United States and other developed markets in Europe and Asia.”

The company’s annual report is due out at the end of the month. The previous one, covering 2013, showed that the company profited $1.5 billion that year: the company’s best year ever.

Still, as of 2015, investors may be concerned with Facebook’s rising costs and diminishing margins—the stock price is down a little over one percent as of this writing.