Facebook was supposed to close the $1 billion Instagram acquisition within the second quarter, which ends in June. However they've updated their SEC filings to make the date less specific. They now expect the deal to close sometime 2012.

The change comes after reports said that the FTC launched a competition probe into a acquisition. The probe itself is routine for acquisions larger than $68.2 million, while the circumstances are not. Facebook is  expected to go public at a $100 billion valuation later this week.

“Facebook is in the middle of the targets of antitrust enforcers,” David Balto, a former policy director at the FTC who now works as an anti-trust lawyer, told Mashable in an interview last week. “There are certain dominant firms that get the most intense scrutiny.”

Expert have estimated the FTC approval to take up to 12 months and Facebook cannot yet integrate Instagram technology or staff into its business. They have also agreed to pay Instagram a $200 million termination fee if the government rejects their deal.