West Ham's managing director Paul Aldridge is to leave after 10 years at Upton Park following the takeover of the club by an Icelandic consortium.
Eggert Magnusson, who led the takeover, will succeed Terry Brown as chairman on Monday and will also serve as executive chairman and chief executive.
Magnusson said: 'I wish Paul well for the future. Working closely with Terry Brown he has done a great job over the last 10 years in keeping the club in good shape and moving forward in often difficult times. This is a natural moment for a change and I know Paul will be a success as he takes on his new challenges.'
Magnusson will be supported by Scott Duxbury, promoted to deputy chief executive and Nick Igoe, finance director.
Aldridge, who joined the club in 1996 and became managing director in 2000, is leaving by mutual consent.
He said: 'It was a very difficult decision to decline the opportunity to join the new board of West Ham United under the chairmanship of Mr Magnusson.
'It has been a privilege to have been part of such a wonderful time in the club's history. I wish Eggert and his new board the very best of luck, I am very confident that the club is in very good hands and that the future for all involved in the club is extremely exciting.'