Shareholders in London Heathrow Airport (LHR) that collectively own more than a third of the UK’s largest gateway have indicated they intend to sell their stakes alongside majority owner Ferrovial.

Spanish infrastructure specialist Ferrovial has already agreed to sell 15% of FGP Topco, Heathrow’s parent company, to French private equity house Ardian, and a further 10% to Saudi Arabia’s Public Investment Fund (PIF). This would see the Madrid-based firm fully divest its holding in a transaction worth £2.4 billion ($3 billion).

Ferrovial says that in accordance with a “tag-along process” as part of the deal, other FGP Topco shareholders are also exercising their rights to sell shares. Their collective shareholding represents 35% of the share capital of FGP Topco, effectively putting 60% of LHR on the market.

A condition of Ferrovial’s sale is that the “tagged” shares are also sold. Ardian or PIF must therefore raise their offer or find other investors to acquire the fresh stakes.

“The agreement for the sale and purchase of [Ferrovial’s] shares in FGP Topco remains in force, although it is a condition for the sale of the shares that the tagged shares are also sold,” a statement from Ferrovial said. “The parties are working toward satisfaction of such condition by exploring different options to satisfy the same.”

The company added that completion of a deal now hinges on “satisfaction of the tag-along condition,” meaning that “there can be no certainty that the transaction will complete.”

Ferrovial has owned a stake in LHR since 2006, leading a consortium that bought BAA following a keenly contested takeover battle. FGP Topco’s shareholders also currently comprise Qatar Investment Authority, Caisse de dépôt et placement du Québec, Singapore-based GIC, Australian Retirement Trust, China Investment Corporation, and Universities Superannuation Scheme.

In November 2023, Ardian said its acquisition fits with its approach of “investing in significant infrastructure in its core markets.” The firm was previously a 49% shareholder of London Luton Airport from 2013 until 2018.

Saudi Arabia’s PIF adds that its planned investment in LHR is “in line with its strategy to support the business as a long-term partner.” It is one of the largest sovereign wealth funds in the world and is controlled by Saudi Crown Prince Mohammed bin Salman.

LHR handled more than 6.6 million passengers in December 2023, marking it the airport’s busiest-ever December. This saw total traffic rise to 79 million for the 2023 calendar year.

Transatlantic travel remained a key driver for passenger numbers, with 1.6 million traveling to and from North America in December, as New York John F. Kennedy Airport clinched the top spot as LHR’s most popular destination in 2023 with more than three million passengers in total.