Facebook has finalized the deal to buy the popular messaging app WhatsApp for $16 Billion, according to the statement released by Facebook yesterday. The $16 Billion price tag consists of $4 Billion in cash and $12 Billion worth of shares in Facebook Inc. upfront to the founders of WhatsApp. The agreement also includes an additional $3 Billion of restricted stock over the course of next four years to the founders and employees of WhatsApp. WhatsApp has around 50 employees.

“WhatsApp’s extremely high user engagement and rapid growth are driven by the simple, powerful and instantaneous messaging capabilities we provide. We’re excited and honored to partner with Mark and Facebook as we continue to bring our product to more people around the world.” – Jan Koum, WhatsApp co-founder and CEO.

WhatsApp is a fast growing real-time mobile messaging app that allows users to send and receive messages over the Internet, avoiding the regular messaging charges. It has currently over 450 million active users with 100 million active users registered in the last four months and is on the path of reaching 1 billion users. Its business model involves charging $1 per year as a subscription fee, which is not charged for the first year.

“WhatsApp will remain autonomous and operate independently. You can continue to enjoy the service for a nominal fee. You can continue to use WhatsApp no matter where in the world you are, or what smartphone you’re using. And you can still count on absolutely no ads interrupting your communication. There would have been no partnership between our two companies if we had to compromise on the core principles that will always define our company, our vision and our product”, Jan Koum, WhatsApp co-founder and CEO, said in a blog post.