French and Saudi investors have put forward a revised offer to acquire additional shares in London Heathrow airport’s operator, after Spanish infrastructure firm Ferrovial and other shareholders opted to divest their interests.

Ferrovial had revealed plans last year to sell its 25% shareholding in FGP Topco – the parent of Heathrow Airport Holdings – to French private equity firm Ardian and the Saudi Arabian Public Investment Fund.

But a tag-along process meant a number of other FGP Topco shareholders took the chance to sell their interests as well.

The parties have been “exploring different options” to satisfy conditions to sell these tag-along shares alongside Ferrovial’s stake.

BA A319-c-Heathrow Airport

Source: Heathrow Airport

London Heathrow is the hub of UK flag-carrier British Airways

As a result, Ardian and the Saudi fund have offered to acquire a total 37.62% share in FGP Topco. Ardian will have around 22.6% with the Saudis holding about 15%.

Ferrovial says this offer is worth just under £3.26 billion ($4.13 billion), up from the £2.37 billion originally agreed for the 25% share.

Under the revised agreement, Ferrovial will retain a 5.25% stake in FGP Topco – part of a combined 10% interest with the tag-along shareholders.

Ferrovial says the transaction is still subject to regulatory approval, and potential exercising of other shareholder rights.

While the Saudi fund has yet to comment, Ardian says it has “worked closely” with the various parties to revise the agreement and “reiterates its strong commitment to investing [in] the UK”.