Facebook said Wednesday it was buying the fast-growing mobile messaging service WhatsApp for more than $16 billion in cash and stock, expanding the global footprint of the social networking giant.
The deal bolsters the world's biggest social network by adding the 450 million users of WhatsApp, which will be operated independently with its own board.
It is Facebook's biggest acquisition and comes less than two years after Mark Zuckerberg's firm raised $16 billion in the richest tech sector public stock offering.
The purchase includes $12 billion in Facebook shares and $4 billion cash. It calls for an additional $3 billion in restricted stock units to be granted to WhatsApp founders and employees that will vest over four years.
"The acquisition supports Facebook and WhatsApp's shared mission to bring more connectivity and utility to the world by delivering core Internet services efficiently and affordably," said a Facebook statement.
Facebook reportedly sought to acquire another hot messaging firm, Snapchat, for $3 billion last year.
"WhatsApp is on a path to connect one billion people. The services that reach that milestone are all incredibly valuable," said Zuckerberg, Facebook founder and chief executive.
"I've known (WhatsApp founder) Jan (Koum) for a long time and I'm excited to partner with him and his team to make the world more open and connected."
WhatsApp is a cross-platform mobile app which allows users to exchange messages without having to pay telecom charges.
"Almost five years ago we started WhatsApp with a simple mission: building a cool product used globally by everybody. Nothing else mattered to us," Koum said in a blog post.
"Today we are announcing a partnership with Facebook that will allow us to continue on that simple mission.
"Doing this will give WhatsApp the flexibility to grow and expand, while giving me, (co-founder) Brian (Acton), and the rest of our team more time to focus on building a communications service that's as fast, affordable and personal as possible."
Biggest ever deal in tech
Facebook's purchase of messaging service WhatsApp for up to $19 billion in cash and stock is one of the largest acquisitions ever in the technology sector.
Here are some other notable deals involving US tech companies, in order of dollar amount from largest to smallest:
HEWLETT-PACKARD BUYS COMPAQ - SEPTEMBER 2001
US technology giant Hewlett-Packard buys Compaq Computer for $25 billion in a bid to compete with IBM.
GOOGLE BUYS MOTOROLA MOBILITY - AUGUST 2011
Internet search giant Google buys the handset business of Motorola for $12.5 billion in a bid to challenge Apple in the smartphone market. Less than three years later, Google sold Motorola to China's Lenovo for $2.91 billion.
HEWLETT-PACKARD BUYS AUTONOMY - AUGUST 2011
US technology giant Hewlett-Packard buys British enterprise software company Autonomy for $10.24 billion. US authorities later open an investigation amid HP accusations that Autonomy had engaged in "accounting improprieties."
MICROSOFT BUYS SKYPE - MAY 2011
Microsoft buys Internet voice and video leader Skype for $8.5 billion, the largest acquisition ever by the US software giant.
ORACLE BUYS SUN - APRIL 2009
US business software giant Oracle buys struggling Sun Microsystems and its Java programming language for $7.4 billion.
MICROSOFT BUYS NOKIA - SEPTEMBER 2013
Microsoft buys the handset business of former market leader Nokia for $7.2 billion in an effort to catch up to rivals Apple and Google in the smartphone market.
GOOGLE BUYS YOUTUBE - OCTOBER 2006
Internet search giant Google buys online video platform YouTube in October 2006 from its founders, Steve Chen and Chad Hurley, for $1.65 billion.
EBAY BUYS PAYPAL - JUNE 2002
Online auction house eBay buys online payments firm PayPal for $1.5 billion.
YAHOO BUYS TUMBLR - MAY 2013
Former Google executive Marissa Mayer makes her biggest purchase since taking over as CEO of Yahoo, buying the popular blogging platform Tumblr for $1.1 billion.
FACEBOOK BUYS INSTAGRAM - APRIL 2012
Facebook offers $1 billion for hot smartphone photo-sharing service Instagram. The purchase of Instagram was Facebook's largest until the WhatsApp deal.