He was adopted in 1945 by Margarita Companc de Pérez Acuña, a local socialite, and enrolled at the La Salle college preparatory school, though he left before graduating.

He married María del Carmen "Munchi" Sundblad Beccar-Varela, an heiress, in 1964, and in 1968, was named director of the Banco Río de La Plata (at the time of the country's largest, private-sector banks), following its purchase by his family.

Molinos Río de la Plata, which sells Luchetti's pasta, Cocinero oils and Nobleza Gaucha yerba mate (among numerous brands), is one of Argentina's leading processed foods companies, earning roughly US$850 million in revenues in 2009.

In a year that saw the Argentine economy shaken by the worst economic turmoil in over a century, Pérez Companc continued to oversee growth in the family's business concerns: the value of the group's consolidated energy, food processing and financial services portfolio grew a healthy 20% during 2001.

[5] He scored a big coup in October 2002 when he announced the sale of the family's 60% share of Petrolera Pérez Companc to Brazilian oil giant Petroleo Brasileiro S.A. (Petrobras) for a reported US$1 billion in cash and bonds.