Facebook have unveiled the final Instagram purchase information in their 10-Q. The social network have stated that the final purchase of Instagram will sit in its accounting as $521 million. This figure came about by adding $300 million in cash that Facebook promised, as well as the 12 million vested shares of Class B common stock.

This common stock was given to "non-employee stockholders", such as investors, but not the staff itself. Facebook have issued 11 million un-vested shares to Instagram's employees, including founders. These shares will vest over a three-year period which have an "aggregate fair value of $194 million". Adding the $521 million and $194 million together, we find ourselves at $715 million.

We did see a $1 billion number floating about when this news hit the wire, but the stock of Facebook has slumped, considerably, since that time.