[1] In 1989, he received a degree in economics and business administration from the San Sebastián campus of the University of Deusto.

[2][5] In the 1990s, Aierdi taught human resources management models at the University of Deusto's Faculty of Economic and Business Sciences.

[2][7] Aierdi has been affiliated with the Basque Nationalist Party (EAJ) since 2003 and was an executive member of its Navarrese branch, the Napar Buru Batzarra (NBB), from 2008 to 2012.

[17] In his ministerial role, Aierdi has been president of various state-owned companies including Sodena, Cener and Naitec.

[4] He came under criticism after Sodena loaned €3 million to Davalor Salud, a company that was in financial difficulties and subsequently went into administration.