Microsoft poised to trump Yahoo in digital ad space

U.S. online giant Yahoo received more bad news on Tuesday on top of its worse-than expected second-quarter results with reports that the technology giant is about to be usurped by rival Microsoft.

Yahoo's share of the global $140.15 billion digital advertising market will fall from 2.86 percent to 2.52 percent during 2014, according to projections by independent market research company eMarketer. The same firm predict that Microsoft will grow its share to 2.54 percent of the market - just enough to surpass Yahoo for the first time.

However, there is some good news: Yahoo's ad revenues will be back in the black this year, increasing its global digital ad revenues by 2.7 percent after a decline of 2.1 percent in 2013, according to the same research.

Read MoreMicrosoft to slash 1,000 jobs in Finland: Report

Getty Images

eMarketer say that it formulates the estimates by analyzing data from a variety of research firms, government agencies, media outlets and company reports.

Yahoo posted quarterly earnings and revenue that failed to match analysts' estimates on Tuesday evening but shares gained in afterhours trading after it said it wouldn't be selling as much of its stake in Chinese online giant Alibaba. Shares, however turned around and were trading lower by 1.8 percent at 10:00 a.m. London time on Wednesday ahead of the U.S. open.

CEO Marissa Mayer addressed concerns over the company's turnaround in Yahoo's earnings conference call , shortly after Tuesday's results.

Read MoreYahoosales outlook weak; shares wobble on Alibaba

"Given our top priority of long-term sustainable growth, we not satisfied," she said. "In the case of Yahoo, I have stated in the past that we believe a transformation of this size and scale will take multiple years. And we continue to believe that is the case today."

Meanwhile, Google is set to comfortably keep its title as the king of online advertising, according to eMarketer. It said it would dominate the global digital ad market this year, netting 31.45 percent of the digital dollars invested by advertisers worldwide. This comes despite it losing a little market share, which has been put down to a sign of its "maturing" ad business in comparison to competitors.

Yahoo CEO: Turnaround could take years
Yahoo CEO: Turnaround could take years

Special mentions were reserved for Facebook and Twitter, with the social media sites both rising up the ranks this year, with the former showing the biggest jump in market shares for any of the companies.

Read MoreApple, with IBM, aims to dominate biz computing

"Both companies are benefiting from their users' shifting behaviors on mobile devices. Facebook is expected to take 22.3 percent of the $32.71 billion global mobile advertising market this year, up from 17.8 percent in 2013," the company predicted in a press release on Tuesday.

"Twitter will continue its ascent in the mobile ad world as well, growing from 2.4 percent last year to 2.8 percent in 2014."