10 assets owned by South Africa’s richest woman, Mary Slack

Feyisayo Ajayi -

Mary Slack, 79, is the wealthiest woman in South Africa. She is the granddaughter of Sir Ernest Oppenheimer, the renowned entrepreneur in diamond and gold mining who controlled De Beers and founded the Anglo-American Corporation of South Africa. Slack is also the daughter of Harry Oppenheimer.

Following the passing of her father, Harry Oppenheimer, in 2000, Slack inherited her share of his fortune and empire alongside her younger brother, Nicky Oppenheimer, who is currently the second richest man in South Africa. While Slack has not appeared on Forbes or Bloomberg Billionaires Index rankings, Billionaires.Africa can confirm that she shares an equal 50-50 stake with her brother, making her South Africa’s wealthiest woman.

Slack is renowned in South Africa for her love of horses and her philanthropic endeavors. She is recognized as a prominent figure in the South African racing industry and a dedicated supporter of thoroughbred breeding. She owns the Wilgerbosdrift stud farm, which has contributed some of the world’s finest thoroughbred bloodlines to horse racing in South Africa.

In the philanthropic sphere, Slack has long been associated with the Oppenheimer Memorial Trust, established by her father in honor of her grandfather. The Oppenheimer Memorial Trust (OMT) provides funding to individuals and organizations in higher education, as well as the education, social justice, and arts and culture sectors.

Apart from her role in the Trust, Slack has been actively involved in fundraising for numerous projects. Her involvement began with Dorkay House, which hosted the African Music and Drama Association in the 1960s. She also served as the managing trustee of the Market Theater from 1989 to 1992 and founded Business and Arts South Africa in 1997. Presently, Mary serves as the chair of the Brenthurst Library and Press, a patron of the South African Mzansi Ballet, and actively participates in the Racing Trust’s work.

In March 2023, Slack made a generous donation of R1 billion ($57 million) to the Solidarity Fund established by South African President Cyril Ramphosa to support vulnerable communities affected by the coronavirus pandemic in South Africa.

Mary Slack manages her extensive fortune through the Mary Oppenheimer Daughters family office (MODO), which operates in Johannesburg, London, and the Isle of Man.

While specific details about asset allocations are closely guarded, MODO oversees more than $3 billion in assets under management, invested in foreign government bonds, stock market indexes, and private equity funds.

Slack’s investments are primarily made through private equity firms where her family serves as anchor investors, including Stockdale Street, Tana Africa, Senqu, and Senqu Capital.

Billionaires.Africa has identified and tracked several assets and holdings associated with Slack. The following are ten investments and properties in which she holds direct ownership or a controlling interest through private equity funds:

  1. MAS P.L.C: In March 2021, Slack acquired a 5.87-percent stake in MAS P.L.C, a commercial property investor and operator listed on the Johannesburg Stock Exchange. The company focuses on acquiring, developing, and operating retail, office, industrial, logistics, and hotel assets in western and central-eastern Europe.
  2. Auria Senior Living: Slack holds the majority share in Auria Senior Living through her South African private equity interests, advised by Stockdale Street. Auria specializes in developing, owning, and operating high-quality senior living communities in South Africa.
  3. Wilgerbosdrift stud farm: Located in the Western Cape, Wilgerbosdrift is a thoroughbred stud farm known for producing exceptional racehorses in South Africa. It continuously strives to enhance its bloodlines and achieve superior results.
  4. Afrifruit: AfriFruit is a Moroccan company focused on cultivating and exporting berries (raspberries, blueberries, and blackberries) from Morocco to European markets. The company operates multiple farms in the Agadir and Moulay Bousselham regions, employing over 1,000 people as of 2019.
  5. Kensington Distillers & Vintners (KDV Group): Founded in 2014, KDV Group is engaged in the production, distribution, and sale of alcoholic beverages, primarily spirits and wines. The group encompasses a portfolio of proprietary brands in categories such as Gin, Whisky, Bitters, Sparkling Wine, and Rum. KDV Group operates manufacturing facilities in South Africa, Kenya, and Nigeria.
  6. Promasidor: Promasidor Group is a privately held fast-moving consumer goods company operating in nine African countries with sales extending to 30 countries. The group offers a range of powdered milk, food seasoning, and tea brands. It holds significant market positions in Anglophone and Francophone West Africa and is expanding its presence in East and Southern Africa.
  7. Mabaret Al Asafra: Mabaret Al Asafra hospital group was founded in 1982 by Dr. Amr Morsi in Alexandria, Egypt. The group operates two hospitals and a laboratory business, Mabaret Asafra Labs, providing high-quality medical services at affordable prices. The hospitals are located in Alexandria East and Alexandria West, with seven branches across prime locations in Alexandria.
  8. SAN Gel: Based in Gabon, SAN Gel is a privately-held company involved in importing, processing, distributing, and retailing frozen and cold food products. It offers a diverse range of items such as poultry, pork, beef, lamb, veal, fish, vegetables, pre-cooked meals, ice creams, and desserts. SAN Gel distributes its products through wholesale channels and its own retail outlets in Libreville, with growth opportunities in Gabon and beyond.
  9. SIAT: SIAT owns approximately 70,000 hectares of natural rubber and palm oil plantations in West Africa across Gabon, Cote d’Ivoire, Nigeria, and Ghana. The company operates palm oil mills and refineries at all its palm oil plantations. SIAT also engages in cattle ranching, cooking oil production, and soap production in Gabon.
  10. Quality Meat Packers: Quality Meat Packers Group is involved in various aspects of animal-sourced meat production, including procurement, farming, hatching, breeding, processing, packaging, distribution, marketing, and retailing. The group consists of Quality Meat Packers, a modern slaughterhouse and meat processing plant, and Anirita Poultry Farm, an integrated poultry producer. QMP Group is certified for halal production and exports its products to Kenya, the UAE, Saudi Arabia, Oman, and other international markets.