The move comes amid serious allegations against Sullivan, 77, raised in a joint investigation by the BBC's Panorama programme and The Times newspaper.
A statement issued jointly by Kretinsky and fellow shareholder Vanessa Gold confirmed the share purchase agreement with the Gold family. Under the deal, 1890 Holdings, part of the wider EP group controlled by Czech billionaire Kretinsky, would acquire additional shares from the Gold family.
That would lift Kretinsky's holding to approximately 43%, overtaking Sullivan's 38.8% stake and making EP the club's biggest shareholder. The agreement remains subject to pre-emption rights held by other shareholders and the necessary regulatory approvals.
"As the largest shareholder, group EP will be able to provide the additional financing the club needs," the statement read.
Kretinsky and Gold said they expect to finalise the transaction within the next couple of weeks. Vanessa Gold inherited her 25.1% stake in West Ham United following the death of her father, David Gold, in January 2023.
Sullivan and the late David Gold bought West Ham together in 2010, with Sullivan having held majority control of the club ever since.
The proposed transaction follows allegations that Sullivan engaged in sexually exploitative and predatory behaviour, claims he has categorically denied.
Kretinsky and Gold addressed the allegations directly in their statement, expressing sympathy for those involved.
"Our thoughts go out to those women who have fought so hard to make their voices heard," they said. "Any abuse of power is abhorrent, and it takes great courage and determination to speak up against it."
The pair also addressed the club's handling of safeguarding measures relating to Sullivan, who has been barred from contact with West Ham's women's and youth teams for the past three years.
They said the wider West Ham board was not informed of the allegations against Sullivan until approximately a month ago. However, the full details of the claims only became apparent when they were made public on Monday.
"As communicated by West Ham, the Board representatives of shareholders other than David Sullivan were only made aware this week of the safeguarding measures that have been in place since 2023," the statement said.
The ownership shift comes at a turbulent moment for West Ham, who were relegated from the Premier League for the first time since 2012 at the end of last season.
Manager Nuno Espirito Santo has agreed to stay on and lead the club's attempt at an immediate return to the top flight, a feat he previously achieved with Wolverhampton Wanderers in 2018.
West Ham posted a loss of £104.2m for the financial year ending 31 May 2025, with another substantial deficit expected this year.
Portugal midfielder Mateus Fernandes has been linked with a move away, with Manchester United among those interested, though the Hammers are said to be holding out for a fee in the region of £80m.
Kretinsky, who first bought into West Ham in November 2021, also holds a significant stake in supermarket group Sainsbury's, giving him substantial personal financial firepower. Kretinsky and Gold said their plans have the backing of fellow shareholders Tripp Smith, Daniel Harris and Terry Brown.
"We are taking these steps because West Ham needs to be truly united at this moment in its history," they said.
Once the deal is completed, group EP and the Gold family have agreed to vote jointly on key club matters going forward. That alliance is intended to support what the statement described as the strategy of targeting an immediate return to the Premier League.
The pair also acknowledged the need to repair relations with supporters, who have staged repeated protests against Sullivan and former vice-chair Karren Brady over the club's running in recent years.
"We are also committed to engaging with our fans and all business partners to build a stronger future for our club," the statement added.
Kretinsky and Gold said their priority now is to stabilise the club, retain key players and back Nuno's promotion push.
"We believe that a strong coalition – of fans, players, management and the board – is essential to securing the bright future this club deserves," they said.
For a club searching for stability after a chaotic season, the message from its two largest shareholders was unambiguous: the era of divided ownership is meant to be over, and the rebuild starts now.