As consumer brands increasingly look to social media platforms as a major tool for marketing campaigns, a recent report by Mediakix estimates that “influencers” on Facebook Inc.’s (FB) Instagram app, including celebrities and overnight internet sensations that promote products to their followers, are now raking in $1 billion on the platform.

As Instagram continues to reel in new users with features such as Instagram Stories, which has striking similarities to Snap Inc.’s (SNAP) Snapchat, influencer marketing is expected to be a $5 billion to $10 billion market by 2020. (See also: Social Media Will Soon Hit 2.5B Users: eMarketer.)

"The fastest growing influencer marketing platforms are Instagram, Instagram Stories, Facebook, and YouTube," said Jeremy Shih, head of marketing at Mediakix, to CNBC.

Influencers—Micro to Mega

Instagram saw its monthly active users (MAUs) in April 2017 jump to 700 million, while recently launched Instagram Stories rose to 200 million users, according to the report. Major brands such as H&M, Adidas AG (ADDYY), American Express Co. (AMEX), Microsoft Corp. (MSFT) and Toyota Motor Co. (TM) have taken to Instagram, paying out anywhere from $50 per post to “micro influencers” to a half a million dollars for a sponsored post from mega influencers such as pop star Ariana Grande.

The news comes as Venice, Calif.-based Snap trades at less than half of its peak initial public offering (IPO) price reached back  in March. The research seems to validate investors’ fears regarding larger tech giants’ investment in Snapchat alternatives. Facebook and its Silicon Valley peers have leveraged their massive cash piles and loyal user bases to generate revenues from advertisers choosing to shy away from traditional advertising such as TV. At the same time, the Street remains skeptical of Snapchat’s ability to squeeze money from its users, as advertisers prefer other social media platforms for their marketing budgets.

“Since 2011, Instagram has been one of the fastest growing social media platforms. In the past six months alone, it’s added more than 100 million users and growth shows no sign of slowing,” read the recent Mediakix report. (See also: Snap Slides to New Lows on Disappointing Earnings and Slowing User Growth.)