Facebook has become one of the most popular social networking sites worldwide. Evidence of the same is the increase in the market share of Facebook that has been recently reported by ROI agency ZenithOptimedia.

According to the reports submitted by the above agency on Monday, Facebook’s market share doubled since 2009. The recent figures have showcased that the advertising market share of the social networking giant has doubled from 1.4% in 2009 to 3.1% in 2010.

Google is undoubtedly dominating the Internet advertising space with its three traditional and big competitors i. e. Microsoft, Yahoo, and AOL at the bottom. Facebook has recently started rising up, which was even underneath the above failing trio some years back.

But, new figures are clearly and primarily mentioning about Facebook’s steady gain in market share in terms of Internet advertising expenditure. Moreover, they are also pointing over overtake that according to them Facebook will soon make over Microsoft, probably by the end of this year.

Though reports are showcasing that the search company is controlling nearly half of the online advertising pie, the overall ad picture (including traditional and new media) highlighted a little dicer state of same last month.

ZenithOptimedia also touted that the overall ad spending of the company will jump 3.5% globally in 2011 and 4.7% in 2012 but, Peter Kafka at AllThingsDigital points out recently that the above figures have now been revised down with October’s forecast of 3.6% and 5.3%, in both the respective years.

“There are those who believe that Facebook and other social networking sites will take eyeballs away and undermine Google. I think people go to Facebook to socialize, not to buy or search for things”, said Mr. Michael Pytosh, Senior Portfolio Manager with the ING Growth and Income Fund (IAGVX) in New York. “When people want to find something they will continue to go to Google”, he added.