Summary:

Twitter has raised a massive new round of funding led by new investor Kleiner Perkins, as it continues its speedy growth. Kara Swisher at Al…

Twitter

Twitter has raised a massive new round of funding led by new investor Kleiner Perkins, as it continues its speedy growth. Kara Swisher at AllThingsD puts the size of the investment, which Twitter isn’t disclosing right now, at $200 million. The valuation is a reported $3.7 billion, more than triple the $1 billion valuation the site last raised money at a year ago.

This funding round was hotly contested with both Kleiner Perkins and Digital Sky Technologies competing to invest in the microblogging service. Late last month, TechCrunch reported that Kleiner Perkins, which has missed out on investing in some of the web’s other recent success stories, was the likely winner.

Twitter isn’t offering any specifics on what it is going to do with the new influx of cash, which brings its total funding to date to $405 million, simply saying that the “additional resources and expertise will be extremely helpful as Twitter continues to grow as a company and business.”

Since raising $100 million in a funding round last September, the company has expanded dramatically, making a series of acquisitions, introducing an ad platform, and redesigning its site in an effort to get more people to use it. The company now has 350 employees, up from 130 a year ago.

Along with the funding, Twitter is adding former Tellme Networks CEO Mike McCue and former DoubleClick CEO David Rosenblatt to its board. Twitter’s existing investors include mutual fund giant T. Rowe Price, Insight Venture Partners, Spark Capital, Institutional Venture Partners, and Union Square Ventures.

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