NEW YORK – The U.S. mobile ad market has jumped significantly this year, more than doubling the $4.26 billion in 2012 to reach $9.6 billion this year, according to eMarketer. The company adjusted its August projection up $1 billion, Online Media Daily reports.

Mobile ads are cannibalizing ad growth on computer (both laptop and desktop), which registered a 1.7% drop in 2013. However, the PC-based advertising arena will come close to $33 billion this year. Overall digital advertising in the United States on all devices will accelerate 15.7% to reach $42.6 billion.

Next year’s forecast is even rosier for mobile ad spending. According to eMarketer, mobile ads will increase 56% to come within striking distance of $15 billion, while desktop ads will advance only 0.4%. Within two years, mobile ad spending will come close to desktop, and by 2017, mobile ad spending will pass PC spending.

The change in mobile advertising is the result of a quicker shift of money from PCs to mobile, especially from Google and Facebook. Mobile will get nearly all the revenue from more spending. Grocery stores are among retailers starting to rely more heavily on mobile coupons and other advertisements to reach shoppers on the go.