West Ham have been sold to a group of Icelandic banks in a deal understood to be worth just over £100m.
The new owners are CB Holding, a company mainly owned by the Straumur-Burdaras investment bank who have appointed one of their senior directors Andrew Bernhardt as the new non-executive chairman.
The new regime have moved swiftly to assure manager Gianfranco Zola and his assistant Steve Clarke that their jobs are safe and that some funds will be made available for transfers. Chief executive Scott Duxbury will also remain at the club.
Bernhardt said in a statement: "I am delighted that an agreement has been reached and look forward to working with Scott Duxbury and his team in the coming years.
"We have one of the best young management partnerships in Gianfranco Zola and Steve Clarke and the team has evolved with a great mix of experience and young players coming through from the academy.
"I can assure fans we will sanction investment in new players, but all within the parameters of sensible budgeting based on revenues generated by West Ham United.
"It will be my job to help facilitate this continued progress on the pitch, while ensuring the club's success is built on a strong financial footing.
"We have an initial two-year plan which includes improving the infrastructure at the club and we will be getting to work on this as soon as the new board is appointed."
Previous owner and chairman Bjorgolfur Gudmundsson, who lost his fortune in the credit crunch, and vice-chairman Asgeir Fridgeirsson have both left the club.
Bernhardt insisted that he viewed the Hammers as already being on the right course.
He added: "CB Holding fully supports the executive management of the club and acknowledges the considerable progress achieved this season by Scott Duxbury and Gianfranco Zola. CB Holding has no intention of changing the executive management or direction of the club."
Duxbury insisted that the uncertainty of recent months had not been laid to rest.
He said: "This is an agreement that will secure the long-term future of this football club. Change is always unsettling, but I believe the new owners led by Andrew Bernhardt will bring stability to West Ham United and I hope all our staff and fans will join me in welcoming them to our club.
"At the same time, my best wishes and thanks go to Bjorgolfur Gudmundsson and Asgeir Fridgeirsson.
"This will allow us all to concentrate on next season and beyond, with Gianfranco Zola, technical director Gianluca Nani and I working to build on what we have achieved. We are all committed to a long-term vision.
"We are playing great football, have our academy at the heart of the club and are looking to the past to move forward in the right way."
Gudmundsson expressed regret at being forced to end his ties with the club.
He said: "I want to thank everybody at Upton Park for unforgettable years. The players, fans, management and staff have all contributed immensely to a period of progress, a period where the club has sharpened its vision, strengthened the first team with young homegrown talents and laid a solid foundation for self-sustainable operations of West Ham United as a strong Premier League football club.
"As my fortunes have changed I now have to withdraw from the board of directors. I do that with a great regret but I am convinced that this change of ownership and control of West Ham United will advance the club in the present circumstances."