It's all about Instagram.

Yes, stock analysts and the media have been saying Instagram is key for almost a year now.

But what if someone told you, the market does't even know how much in additional earnings dollars Instagrammcould bring Facebook (FB - Get Report) ?

Here's what to listen for when management reports Facebook's quarterly earnings on July 24. 

'Explore' Ads

Facebook's effort to monetize Instagram 'stories' is well documented, but the social media giant keeps finding ways to create new revenue streams on Instagram. 

Instagram's 'Explore' platform is in the early stages of monetization. Morgan Stanley analyst Brian Nowak wrote in a June note, Explore ads could add $1 billion of revenue to Facebook by 2021 and about 2% to earnings per share.

E-Commerce

Also, Nowak had previously written that Facebook's initiatives to create an e-commerce model for its ads could add $4 billion in revenue in 2021. Instagram users have been showing more intent to purchase of late, which gives Facebook the leverage to raise prices. Facebook's Instagram, Nowak says, has a high return on ad spend. He says Facebook can charge a 10% sales commission when user buy an advertisers' product. 

Long-term investors can listen for management comments on the emerging trends on Instagram monetization, which the market may not fully appreciate yet, as the extent of the earnings accretion from those trends is still unknown. Facebook trades at 21 times forward one-year earnings, very low compared to where that multiple has reached in the past. 

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