U.S. mobile ad spending is expected to nearly triple in size for 2012, according to revised estimates from eMarketer. The research firm said the total would amount to a little over $4 billion this year, from the $1.45 billion recorded in 2011.

Meanwhile, growth for next year is anticipated to be approximately 77%, to total around $7.2 billion. For 2014, those figures are 55% and slightly over $11 billion, respectively.

eMarketer's new 2012 estimate is substantially higher than the prediction it made this past September; then, it anticipated $2.6 billion in spending for the full year. It attributed its revision to the success of proprietary mobile ad platforms such as those that Facebook (NASDAQ:FB) and Google (NASDAQ:GOOGL) use. The reseracher termed the former's growth in the mobile ad sphere "astonishing," while according to its estimates Google will almost triple its mobile ad revenues this year.

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