Facebook, in their continued desire for a messaging platform, has agreed to purchase WhatsApp. The selling price is a whopping $16 billion in cash and Facebook stock, plus $3 billion in Restricted Stock Awards, or RSA. A regulatory filing details all the subtleties, but for now — we’re going to sit back and marvel at that price.

Of the $16 billion, $4 billion will be straight up cash — close to the $3 billion we heard Facebook offered for Snapchat. The remaining $12 billion will be Facebook common stock, while the $3 billion in RSU is for employee retention. There is a failsafe included, wherein Facebook will be charged $1 billion in cash and $1 billion in common shares should the deal not meet regulatory hurdles.

Facebook says WhatsApp has over 450 million Monthly Active Users, which is likely the main attraction here. Via a blog post, Facebook says WhatsApp will remain a standalone service and app. WhatsApp will also retain its branding.

This undoubtedly points the finger at advertisements, where Facebook has been focussed for some time. The failed acquisition of Snapchat was said to be almost all about mobile ads, and absorbing the monthly userbase. Of those 450 million monthly users, Facebook says 70% are also active on a daily basis.

Via the blog post, Mark Zuckerberg, Facebook CEO said “WhatsApp is on a path to connect 1 billion people. The services that reach that milestone are all incredibly valuable. I’ve known Jan for a long time and I’m excited to partner with him and his team to make the world more open and connected.” WhatsApp CEO and founder Jan Kroum added “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.”