Facebook, which turns 10 next week, said Wednesday that more than half of its advertising revenue now comes from mobile. That's a big milestone considering it only started showing mobile ads in 2012. Investors fretted at the time that it wouldn't be able to evolve into a "mobile-first" company. The quarter's results are a sign that it has.
At the end of 2013, more than three-quarters of Facebook's 1.23 billion users - 945 million - logged in using their mobile devices at least once a month.
Facebook's stock is up $8.77, or 16 percent, to $62.30 in midday trading. It hit a record high of $62.44 earlier.