West Ham have completed the signing of Swansea forward Andre Ayew.
The Ghana international scored 12 Premier League goals for the Swans last season, having joined the club in June 2015.
Hammers co-chairman David Gold confirmed the transfer on Twitter, writing: "Andre Morgan Ayew, also known as Dede Ayew is a Ghanaian international, joins West Ham on a four year deal."
Ayew joins West Ham for a club-record fee, reported to be £20million, having agreed a three-year deal.
"I am very proud and happy to be at this magnificent club," Ayew said. "I am happy to be playing for these fans and I hope to make the people very happy here.
"The club have a lot of ambition and have a great manager. They want to become a bigger club every year and with the new stadium and a new training ground, you can feel they are moving onto another level and I want to be part of this project.
"I want to train hard, do my job and show that I deserve to play for West Ham United. I want to give back to the manager and the fans the confidence they are showing me."
West Ham have also added to their defensive ranks with the signing of 22-year-old left-back Arthur Masuaku from Olympiacos.
The former France Under-19 international won two Greek Superleague titles, as well as the Greek Cup, during his two-year stint with Olympiacos.