Information is available in Haik Patapan's Arti Etovpia ev Hay kaghoute, published in Venice in 1930.
Hrant Minassian was an uncle of Matig Kevorkoff. He had been associated to him for his business for almost 50 years, until 1924. At this date, he started to work alone.
In 1930, Patapan's book cited the "Maison Minassian", together with "Maison Kevorkoff", among the most prominent Armenian trade-houses in Ethiopia. The "Maison Minassian" had its central office in Dire Dawa, but held also shops in Harar and Addis Ababa.