Born in Bilbao on 17 June 1948 to a bourgeois family, son to an engineer (father) of Valencian origin and a cultivated mother, daughter of a German physician of Jewish ancestry.

[2] He graduated with degrees in economics and law in 1971 and 1972, respectively, from the also Jesuit University of Deusto in Bilbao, and completed follow-up studies at the École pratique des hautes études in Paris, from 1970 to 1971.

[3] Almunia was chief economist of the Unión General de Trabajadores (UGT), a trade union linked to the Spanish Socialist Workers' Party (PSOE), from 1976 to 1979.

Borrell ran as the underdog, campaigning as the candidate of the socialist base against the party establishment, which largely supported Almunia, including former Prime Minister González.

[13][14] Thus began an uneasy relationship and power-sharing —the "bicefalia" (duumvirate)— between the official party leader, Almunia, and the prime ministerial candidate elected by the members in the primaries, Borrell.

As EU Commissioner for Competition, Almunia was in charge of state aid and antitrust investigations relating to Google[19] and to the tax planning practices of Apple, Starbucks and Fiat,[20] as well as Amazon.