Spanish airport operator Ferrovial is to sell a 10% stake in BAA, the operator of Heathrow airport.
Chief executive Inigo Meiras said the partial sale would help the Spanish company establish a market value for its stake.
Proceeds will be used to fund other investments and to pay down debt.
The Spanish operator currently owns almost 56% of the consortium that bought BAA in 2006.
The BBC reports BAA operates six airports in Britain: Heathrow and Stansted at London, Glasgow, Edinburgh and Aberdeen in Scotland, and Southampton airport.
The company handles about one million flights and 110 million passengers each year.
