Microsoft has just dropped $137 Million into Uber's latest round of funding according to Tech Times. The ride-sharing giant is now valued at $51 billion, making it the most valuable private company in the world. It trumps other giants like smartphone manufacturer Xiaomi and accommodation sharing service Airbnb.

All in all, Uber raked in an impressive $1 billion during this round of funding. Tech website Endgadget notes that Uber got to this stage two years faster than social media colossus Facebook did a few years ago.

"We filed to authorize this new funding more than two months ago," said Uber spokeswoman Kristin Carvell, "The filing is available to the public. We aren't commenting on additional speculation."

The big investment is part of a growing relationship between Uber and the Redmond, WA based software giant. The Tech Times report notes that Microsoft sold a small part of its Bing mapping service to Uber. A hundred Microsoft employees who previously worked on Bing's map features were also acquired in the deal.

Additionally, Uber is being integrated into Cortana, Microsoft's new voice powered assistant which made its debut during last week's Windows 10 release. Uber users can use Cortana to hail a ride and it has the ability to automatically book a car for you based on your calendar.

Uber was founded in 2009 by Travis Kalanick and Garrett Camp and has since expanded to more than 300 cities in at least 57 countries. The company has grown into one of the most influential in the world, with many taxi and transportation companies trying to put the brakes on their approach to public transport via strikes and protests around the globe.