Here They Go Again—ABBA Reunite for First New Album in 40 Years

(L-R) Swedish pop group Abba: Benny Andersson, Anni-Frid Lyngstad, Agnetha Faltskog, and Bjorn Ulvaeus pose after winning the Swedish branch of the Eurovision Song Contest with their song "Waterloo", on Feb. 9, 1974. Olle Lindeborg/TT News Agency via Reuters

STOCKHOLM—Swedish supergroup ABBA announced their first new album in four decades on Thursday and said they would stage a series of virtual concerts using digital avatars of themselves in London next year.

Fans piled online to celebrate the long-awaited reunion of one of the world’s most successful bands. “2021 has been saved by new ABBA music,” @elliemiles23 said in one widely shared Twitter post.