The Spanish infrastructure giant bought the airport for £35 million in 2003.
The sale follows proposals by the Competition Commission that BAA cease running two of its three London airports – Heathrow, Gatwick and Stansted. It also recommended that BAA lose control of either Edinburgh or Glasgow airport.
In a preliminary report, published two weeks ago, the CC said there were competition problems at each of BAA's seven UK airports "with adverse consequences for passengers and airlines".
Completion of the sale is expected to take place towards the end of the month.
Ferrovial acquired BAA in June 2006.