Instagram now at more than 400 million users

The photo-sharing app has grown rapidly over the past three years, faster than many of its social app competitors, including Twitter and Snapchat. The Facebook unit has rolled out a number of products and features this year aimed at getting users to spend more time in the app.

More than 75 percent of Instagram's users are outside the United States, the company wrote in a blog post. More than half of the 100 million newest users living in Europe and Asia with Brazil, Japan and Indonesia adding the most users.

Facebook bought Instagram in 2012 for $1 billion and has been slow to monetize the app. It recently expanded its platform to all advertisers, rather than a select few, and is expected to make up to $2.8 billion in advertising revenue in 2017, according to eMarketer, a research firm.