Facebook closed its purchase of WhatsApp, a fast growing mobile-messaging service, for as much as US$19 billion on Monday.

“We hope to connect to more people worldwide and enhance the quality of WhatApp for our customers,” it said in a statement which was quoted by The Wall Street Journal.

With the acquisition, WhatApp co-founder Jan Koum has been appointed as a member of Facebook’s board of directors and will remain as chief executive of WhatsApp.

According to a statement by the US Securities and Exchange Commission on Monday, Koum will be receiving US$1 million in annual base salary and restricted stock units worth nearly US$2 billion, the same as that of Facebook CEO, Mark Zuckerberg.

Brian Acton, the other co-founder of WhatsApp meanwhile, will remain with the company under terms of the acquisition, which promises ‘inducement grants’ of millions of shares of stock, said Facebook.

The WhatsApp acquisition cements Facebook’s hold on two popular global social applications, apart from Instagram.