Twitter is close to securing as much as $100 million of new capital from mutual fund giant T. Rowe Price, private equity firm Insight Venture Partners and five other investors, the Wall Street Journal reported on Thursday.

The funding will value the fast-growing microblogging site at about $1 billion. Other investors include existing Twitter backers Spark Capital and Institutional Venture Partners, the Journal said, citing people familiar with the deal.

If it goes ahead, the $100 million investment -- twice as much as Twitter had been expected to get in its latest round of fundraising -- would underscore investors' mounting interest in the 2-year-old company, which hosts short, stream-of-consciousness text messages on its website.

The participation of T. Rowe Price, a mutual fund known more for investments in public companies than in start-ups, stirred speculation that Twitter could be moving toward an eventual public offering or acquisition.

You only see this type of behavior typically when a fund is seeking to get a position before an IPO, said Brigantine Advisors analyst Colin Gillis.

Twitter has become an Internet sensation in its 3-year history, with worldwide visitors to its site hitting 44.5 million in June, up 15-fold from a year earlier, according to comScore data. But the San Francisco-based company has only just begun to focus on making money from its free service.

Twitter executives have cited premium features and advertising as key initiatives to make money, though co-founder Biz Stone told Reuters this week that Twitter would not take advertising this year, despite widespread speculation that it would.

VALUE OF INDEPENDENCE

Sanford Bernstein analyst Jeff Lindsay said there was an expectation that Twitter will eventually be acquired, citing Google Inc, Yahoo Inc and Time Warner Inc's AOL as potential buyers.

Anybody who is taking a position like that is taking a bet that either they (Twitter) find a business model -- which they haven't yet -- or more likely that someone with a lot of money burning a hole in their pocket will buy them, Lindsay said.

Twitter did not return calls for comment. The company has said in the past that it intends to remain independent.

Its past investors included Benchmark Capital and Union Square Ventures, Charles River Ventures and Bezos Expeditions, which manages Amazon.com chief Jeff Bezos' personal investments, according to ThomsonReuters data.

A February round of funding, led by Institutional Venture Partners and Benchmark Capital, had valued Twitter at about $250 million. The pair jointly invested $35 million in Twitter during that round.

(Reporting by Alexei Oreskovic and Edwin Chan; Additional reporting by Anupreeta Das in New York, Jim Finkle in Boston and Lisa Baertlein and Alexander Haislip in Los Angeles; Editing by Richard Chang)