(Reuters) - Facebook Inc (FB.O) shares surged 15.5 percent on Thursday, their biggest percentage increase since July 2013, after the social networking service posted quarterly results that blew away expectations on every key measure.
Facebook shares closed at $109.11, putting its market capitalization at about $308.6 billion. That would make it the fourth most valuable technology company, overtaking Amazon.com Inc (AMZN.O), which was valued at about $296 billion ahead of its results on Thursday.
Facebook's strong quarter contrasted with a disappointing performance by Apple Inc (AAPL.O), which is worth about $519 billion, making it the most valuable U.S. company.
"FB has built a remarkable ad platform that enables marketers of all stripes to serve targeted ads to nearly every consumer on the planet," Jefferies analysts wrote.
Facebook said it had 1.59 billion monthly active users as of Dec. 31, about one in every four people in the world.
Mobile ad revenue accounted for 80 percent of total ad revenue in the quarter compared with 69 percent a year earlier.
"FB saw nothing that indicated macro weakness, and we think results bode well for other online ad names like Alphabet (GOOGL.O)," Jefferies analysts added.
At least 22 brokerages raised price targets on Facebook's stock.
Google-owner Alphabet, valued at $500 billion and closing in on Apple, will report results on Monday.
The median stock price target of the analysts tracked by Reuters was $138 on Thursday, suggesting that Facebook could add $123 billion in market value over the next 12 months.
Piper Jaffray was the most bullish, raising its target to $170 from $155.
"We believe Facebook is well positioned to increase its share of digital ad spend as well as to help grow the overall category given its reach and effectiveness for advertisers," Goldman Sachs analysts said in a client note.
Facebook's photo-sharing service Instagram, in particular, is poised to become a material contributor to revenue in 2016, the analysts said.
Reporting by Sayantani Ghosh in Bengaluru; Additional reporting by Tenzin Pema; Editing by Saumyadeb Chakrabarty, Ted Kerr and David Gregorio