Everton completed the signing of Swansea defender Ashley Williams and the South Wales club's chairman Huw Jenkins was downcast with the Wales international's departure.
"We are disappointed to lose Ashley. It is definitely not something we wanted to happen.
"But having turned down Everton's initial offer, Ashley expressed his desire for a new challenge at this time of his career.
"Taking into account the excellent service Ashley has given this football club over the last eight years, including as club captain, we reluctantly agreed to his request to join Everton after they made an improved offer.
"It goes without saying that we wish him the very best with his new challenge and thank him for his services."