He is co-owner and Chief Executive Officer of the Reitan Group. In 1979 he established the grocery chain store REMA 1000, which came to be a great success. By 1990 every village in Norway with more than 10,000 inhabitants had a Rema 1000 shop.
During the 1990s the chain expanded in Denmark, Sweden, Poland, Hungary and Slovakia.
Reitan played keyboard in the music group Four Jets in the 1960s. He and his was the subject of an editorial in Klassekampen.
The editorial highlighted his idea of him governing Norway without being elected by popular vote. His idea is that he could be appointed by Norway"s king.
The editorial described these ideas as "undemocratic dirt".
In 2013 he awarded Norwegian kroner 2 million to Anlov Mathiesen (chief editor of =Oslo), saying that Mathiesen"s work contributes to "increased self-respect for the vendors of the street magazines.".