NEW YORK – A research firm says it expects Facebook’s mobile ad revenue to soar this year, hitting nearly $1 billion a year after the company started to splice ads into its users’ mobile phones and tablet computers.

Wednesday’s forecast came a day before Facebook holds an event to unveil a new Android product. Speculation has centered on a mobile phone, made by HTC Corp., that deeply integrates Facebook into the Android operating system. The move comes as Facebook works to evolve from its Web-based roots to a “mobile-first” company, as its mantra goes.

EMarketer said it expects Facebook Inc. to reap $965 million in U.S. mobile ad revenue in 2013. That’s about 2.5 times the $391 million in 2012, the first year that Facebook started showing mobile ads.

More than half of Facebook’s 1.06 billion monthly users access it on a mobile device.Shares of Facebook rose 83 cents, or 3.3 percent, to close Wednesday at $26.25. The stock is down about 1 percent since the start of the year.