Sunderland have sacked manager Chris Coleman after failing to keep the club in the Sky Bet Championship.
The club have also announced that its owner, Ellis Short, has agreed to sell the club to a group led by Stewart Donald, the chairman of National League side Eastleigh.
Coleman left his role as Wales national team boss to succeed Simon Grayson at the Stadium of Light last November.
But the 47-year-old could not prevent the Black Cats from suffering relegation during his five months in charge.
A statement on the club's official website read: "Sunderland AFC announces that manager Chris Coleman and his assistant Kit Symons have been released from their contracts.
"The club would like to place on record its sincere thanks to Chris and Kit for their tireless efforts in what has been a hugely disappointing season for everyone involved with the club.
"The club is unable to make further comment at this time."
Fifteen minutes after Coleman's sacking, Sunderland announced the owner's intention to sell.
The deal between Short and Donald, who will now relinquish ownership of Eastleigh, is subject to English Football League approval.
Short oversaw a decade of Premier League football while in charge, but will leave with the club having suffered back-to-back relegations.
He said in a statement: "It is no secret that I have been trying to sell Sunderland, but I have waited until the right group came along that have the experience, finances and plan to take this great club back to where it deserves to be.
"I was determined to ensure that I leave Sunderland in the best possible hands and in the best possible state to turn the corner."
Donald said: "All of us involved in this bid believe that Sunderland represents an extraordinary opportunity. Our group have all been involved in building - or rebuilding - football clubs to reach their potential and we believe that over the last decade we have acquired the necessary skillsets to overcome the many challenges that will face us at this huge club."
Donald also released a statement on Eastleigh's website, in which he said: "Eastleigh has become, and will always be, extremely close to my heart. I have always tried to look after the club to the best of my ability and this will never be more important than now when considering prospective new owner/s.
"The football club is in the strongest financial position it has ever been in. With a much-improved stadium and increased revenues enabling the club the ability to seriously compete in the top tier of non-league football and whilst I have been unable to deliver league football, I hope the fans will reflect on my chairmanship as a positive one."