Ferrovial sells part of Heathrow stake to UK pension group

* Ferrovial sells 8.65 pct stake for 392 mln stg

* Remains single biggest shareholder after sale

MADRID/LONDON, Oct (KOSDAQ: 039200.KQ - news) 22 (Reuters) - Spain's Ferrovial has sold part of its stake in Heathrow Airport Holdings (HAH) to a British pensions group as part of a 392 million pound ($636 million) deal.

Ferrovial's disposal of 8.65 percent to Britain's Universities Superannuation Scheme (USS) is the Spanish group's latest sale from its holding in the airport company which owns London's Heathrow and three other airports in the UK.

Following the deal, the Spanish company will have a 25 percent holding meaning it is still the biggest shareholder in HAH, owned by a consortium including Britannia Airport Partners and Singapore's GIC (KOSDAQ: 019570.KQ - news) , Qatar Holding and Alinda Capital Partners.

Ferrovial, which sold a 10.6 percent stake in HAH to Qatar last year for 607 million euros and 5.88 percent to Alinda for 325 million euros in 2011, said on Tuesday the sale was part of its investment diversification strategy.

USS said the purchase, valued at 463 million euros, was its biggest investment in British infrastructure to date.

"USS is investing for the long term. We have confidence that the right incentives will be set in place to encourage the investment that Heathrow and the UK needs," USS Investment Management's Michael Powell said in a statement.

Heathrow airport is facing a number of uncertainties.

HAH said earlier in October it was reconsidering its investment plans following a proposal by Britain's aviation regulator to cap the prices it charges as this would reduce returns to below the level at which shareholders were willing to invest.

HAH also wants to build a new runway at Heathrow but the Conservative-led government overturned a decision to do so after it came to power in 2010, and a number of alternative proposals to expanding Heathrow are currently on the table.

A government commission is due to reach a final verdict on the matter in mid-2015.

Ferrovial bought Heathrow, Britain's busiest airport, and a number of other UK airports as part of its acquisition of BAA in 2006 for 10.3 billion pounds in a highly-leveraged deal.

In 2006, BAA also owned Gatwick, the country's second busiest airport, and Edinburgh airport, but the group has since sold those two to meet regulatory demands and has subsequently been renamed HAH.