Celtic chief executive Dominic McKay has quit the club after just five months, with the club citing “personal reasons” for his departure.
The Parkhead club made the announcement to the Stock Exchange on Friday afternoon.
He will be replaced on a temporary basis by the club’s legal director Michael Nicholson.
A club statement read: “Celtic Football Club announced today that chief executive Dom McKay stood down from his position as chief executive for personal reasons.
“The directors are pleased to confirm that Michael Nicholson, the club’s current director of legal and football affairs, will assume the role of acting chief executive officer and director of the company.
“Michael has been a senior executive of Celtic for eight years and has been at the heart of decision making at Celtic working closely with the CEO and the football department.”
McKay, who held a similar role at Scottish Rugby, was appointed earlier this year as the successor to Peter Lawwell, who decided to retire after 17 years in the role.
The 43-year-old, whose Twitter account was not active on Friday, said: “I’d like to thank the board and everyone at Celtic for their support and wish everyone at Celtic every success for the future.”
Though McKay was serving a notice period at Scottish Rugby, where he had worked since 2008, Celtic negotiated an early release so that he could begin work three months earlier than planned. McKay moved to Parkhead on April 19 but only officially succeeded Lawwell on July 1.
Celtic went into a transitional period at the time of his arrival, having lost their grip on all three domestic trophies after a period of unprecedented success, and dealing with not only Lawwell’s departure, but a managerial change and large turnover of playing staff.
McKay played a key role in appointing Ange Postecoglou as manager after the long-running pursuit of Eddie Howe collapsed, and negotiated a number of transfers as Postecoglou brought in new faces to reshape the squad.
The unexpected announcement means a step up for Nicholson, who Celtic chairman Ian Bankier described as “a team player”.
“It has been my pleasure to work closely with Michael for more than eight years now,” Mr Bankier said. “Having been at the heart of the senior executive and reporting to the board, he has a solid grip on how to achieve our immediate and future objectives.
“Michael is an absolute team player and he will lead an experienced and talented team of executives and colleagues at Celtic.
“Everyone at Celtic will of course work collectively and focus strongly on ensuring we continue to drive the club forward in every area, on and off the field.
“The board, Ange, our management team and all our staff will continue to work together with the ultimate objective, as always, of delivering success for our supporters.”