(Reuters) - Microsoft Corp is expected to surpass Yahoo Inc for the first time in the $140.2 billion worldwide digital advertising market, according to estimates by research firm eMarketer released on Tuesday.
Microsoft's global ad revenue share for 2014 is forecast at 2.54 percent, edging ahead of Yahoo's 2.52 percent share.
Google Inc will remain No. 1 with a 31.54 percent share, trailed by Facebook Inc with 7.79 percent, the research firm said.
Facebook and Twitter are expected to have the largest gains in market share, with Facebook rising from 5.82 percent in 2013 while Twitter Inc's share should grow to 0.79 percent this year from 0.5 percent in 2013.
Google, Facebook, Twitter, AOL and Yahoo, along with other social media and internet companies, depend heavily on advertising for revenue and profit.
Yahoo is expected to report its second quarter results later on Tuesday as it struggles to keep growing its core advertising business.
(Reporting by Jennifer Saba in New York; Editing by Phil Berlowitz)