Reportedly, Twitter‘s value has more than doubled in 9 months, receiving an $8.4 billion valuation. The company landed an $800 million investment just this week by Russian venture firm, Digital Sky Technologies.

It was back in December 2010 that Twitter was valued at $3.7 million, which makes this new number a 127% increase.

Yuri Milner, owner of Digital Sky Technologies, said “Twitter is one of the few companies that has truly changed the world. Twitter’s astonishing growth is a testament to how important it is becoming to more people every day and why we couldn’t pass up the chance to be a bigger part of its future.”

It was just last week that Twitter began rolling out its Promoted Tweets, which had already partnered with some big name companies such as Best Western, Dell, Gatorade, Groupon and Starbucks.

On August 1st, Twitter posted on their official blog some number growth updates, along with the funding announcement. They said, “Twitter continues to grow around the globe at a record pace. Just a year ago, we delivered 65 million Tweets a day. Today, we generate over 200 million Tweets per day. One year ago, there were approximately 150,000 registered Twitter apps. Now, there are more than one million that connect to Twitter. And our team has grown from 250 people to more than 600 in the past 12 months.”

Amazing numbers being released aren’t they?