Instagram is a 2-year-old photograph-sharing Web site, the Los Angeles Times reported.
The sale will mean a huge payday for the firm's owners and leave "a portion" of about $100 million to be divided up among the firm's 13 employees, Wired reported Monday.
As for founder Keven Systrom, who owns 40 percent of the company, he will net about $400 million from the deal. Co-founder Mike Krieger owns 10 percent and will see a return of about $100 million.
Venture capital firm Benchmark Capital owns 18 percent while investment firms Andreessen Horowitz and Baseline Ventures each own 10 percent, Wired said.
Zuckerberg said Facebook would "be mindful about keeping and building on Instagram's strengths and features rather than just trying to integrate everything into Facebook," Zuckerberg said in an online posting.
"That's why we're committed to building and growing Instagram independently," he said. "Millions of people around the world love the Instagram app and the brand associated with it."
Facebook has generally acquired only small companies to get their pools of talent.
"This is the first time we've ever acquired a product and company with so many users," Zuckerberg said.
And, Zuckerberg said, it might be the last.
"We don't plan on doing many more of these, if any at all," he wrote.