Ad revenue from the photo-sharing site that Facebook bought in 2012 will be "almost easy money," Mahaney said at Business Insider's IGNITION conference earlier this month.
He believes that Instagram will be printing cash, thanks to Facebook's decision in September to open its ad platform to advertisers of all sizes, and allow them to reach specific audiences using Facebook's ad targeting tools.
That change led to a surge of new advertisers, as well as increased ad spend. MEC Global's head of social media for North America, Noah Mallin, said recently that he's seen spend on Instagram increase by 11,000%, with clients allocating additional budgets for the service, instead of cannibalizing their Facebook spend.
That's the kind of trend Mahaney expects to continue in the new year.
"Zuckerberg took two months off for the birth of his first child, but Mark, you can take four months off!" he said on stage, referring to Zuckerberg's paternity leave, which started in November. "This revenue is given to you."
Here's the slide that Mahaney presented on Instagram.
Mark Mahaney