The co-founder of German hard discounter Aldi has died at the age of 88.

Theo Albrecht owned the Aldi Nord division of the business, created following a division of the assets of the business with his brother Karl in the 1960s. Karl retained Aldi Sud, which now includes the UK business.

Forbes magazine ranked Theo Albrecht as the 31st richest man in the world this year with a fortune estimated at $16.7bn. Famously reclusive since being kidnapped in 1971, he had not been interviewed or photographed for decades.

The Albrechts pioneered the grocery hard discount model, selling almost entirely private label product, and made an impact on food retailing around the world with Aldi’s rock bottom prices and highly efficient sourcing and operational models.

Aldi Nord operates entirely in mainland Europe, but Theo Albrecht also owned Trader Joe’s, the pioneering US discount chain which he bought in 1979.