Twitter has revealed it has completed a new round of funding, but it's the amount the funding values the social networking site at that's making headlines.

Two anonymous sources have told Bloomberg that the amount Twitter has received is $100 million, and adds up to a 10% stake. This therefore means that the investors see Twitter's overall value as $1 billion.

Twitter has confirmed the investments, and the names of the companies in a blog post, but makes no mention of amount, other than it is "significant". From Twitter's Evan Williams:

"There's a lot of talk today about our financing. Yesterday we closed a significant round of funding with a group of investment firms that we're excited to publicly thank: Insight Venture Partners, T. Rowe Price, Institutional Venture Partners, Spark Capital, Benchmark Capital, and Morgan Stanley".

"It's interesting to see, almost 10 years since we had the first Internet bubble, that we've now got billion-dollar valuations on companies that haven't defined how they're going to monetize their traffic", David Garrity, principal at GVA Research LLC in New York commented to Bloomberg.