By Sitaraman Shankar
DUBAI (Reuters) - Saudi billionaire Prince Alwaleed bin Talal, an investor in some of the world's top companies, on Monday unveiled a $300 million stake purchase in fast-growing microblogging site Twitter, gaining another foothold in the global media industry.
Alwaleed, a nephew of the Saudi king with a personal net worth estimated by Forbes magazine in March to be just below $20 billion, already owns a 7-percent stake in News Corp and has unveiled plans to start a cable news channel.
The Twitter stake, bought jointly by Alwaleed and his Kingdom Holding Co investment firm, resulted from "months of negotiations," Kingdom said in a statement.
Applying an $8 billion valuation figure for Twitter used by some analysts, the investment by Alwaleed and Kingdom amounts to a 3.75-percent stake.
Twitter, which allows people to send 140-character text messages, or Tweets, to groups of so-called followers, is one of the Web's most popular social networking services, along with Facebook and Zynga.
The company said in September that was in no hurry to undertake a hotly anticipated initial public offering. It raised $400 million in venture capital financing this summer.
It now counts more than 100 million active users who log onto the service at least once a month.
Facebook, the world's largest social network has more than 750 million active users.
Internet search giant Google Inc recently launched a social networking service dubbed Google+ which some observers say could lure users away from Twitter.
The use of Twitter played a role in the spread of information in the Arab Spring, a series of revolts that have shaken the Middle East and North Africa this year.
Saudi Arabia headed off some rumblings of dissent from its own population by unveiling a $130 billion social spending package.
Saudis are increasingly turning to satellite television, online news providers and social networking to stay abreast of world events. The world's No. 1 oil exporter announced a series of stricter regulations for journalists earlier this year.
Alwaleed, who has a sizeable stake in Citigroup, has spoken out in favour of broader political participation, fair elections and effective job creation across the Arab world.
Kingdom owns a near-30 percent stake in Saudi Research and Marketing Group, which runs a range of media titles.
"Our investment in Twitter reaffirms our ability in identifying suitable opportunities to invest in promising, high-growth businesses with a global impact," Alwaleed said in the statement.
Shares in Saudi companies are due to start trading at 0800 GMT. Kingdom stock closed on Sunday at 7.85 riyals.
(Reporting by Sitaraman Shankar; Editing by Amran Abocar)