In its first public earnings report last week, Facebook revealed that its active userbase increased 29% on-year to 955 million people, with about 552 million using the service daily, up 32%. However, according to information released in its 10-Q filing this week, approximately 8.7% of active Facebook accounts (83.09 million) don't represent real people.

That figure has sharply increased from March's pre-IPO estimate of 5 to 6% accounts, though CNET says this is likely the result of Facebook adjusting the way it calculates bogus profiles. The site also adds that someone can qualify as an "active" Facebook user if they use the service to login on other sites, but don't necessarily visit the social network.

The document shows that 4.8% of Facebook's monthly active users (MAUs) are duplicates or an extra account someone created in addition to their main profile, whether by mistake, to cheat in social games or for various other reasons. This violates the site's terms of service and Facebook says it's constantly trying to detect and suppress such behavior.

Another 2.4% of the MAUs are said to be "misclassified," meaning someone created a personal profile for a non-human such as a pet or business. These types of entities are permitted on Facebook, but only as "Pages," which differ from standard profiles. The remaining 1.5% of MAUs are deemed "undesirable" for nefarious activities such as spamming.

This news follows days after a small startup publicly withdrew from Facebook, claiming that 80% of the site's ad clicks were from bots. The social network's $38 share price has seen a steady decline since its public debut in May. Shares fell below $20 for the first time Thursday, though the market closed at $20.04, down 4.02% from Wednesday.