In 1993, Feldman auctioned the "Bordeaux Cover", which comprised the 1847 1d Orange-red and the 2d Deep Blue Mauritius "Post Office" stamps, which brought 6,175,000 Swiss francs[1] including all commissions, at that time the highest price ever paid for any philatelic item.
His early life was in Dublin, Ireland, where he started a stamp exchange scheme with school classmates at eight years of age.
[3] When the Handbook of Irish Philately was published in 1968, Feldman presented a copy to the President of Ireland, Éamon de Valera.
[4] David Feldman was a member of the Philatelic Advisory Committee to the Irish Minister for Posts and Telegraphs, from 1975 to 1981, with Robson Lowe and other distinguished philatelists.
Headquartered in Geneva, Switzerland, it held major auctions in paintings, watches, jewellery, art-deco, art nouveau and objets d'arts in centres all over the world.
Ranked as the world's third biggest auctioneer [by volume of sales],[6] with Feldman as CEO, the company established world records selling a Patek Philippe watch "Le Calibre" at 5 million Swiss francs[7] and "La Rhubarbe",[8] a piece of Galle glass at 1.5 million Swiss francs in 1988.
In 2004 Feldman was mandated by Elizabeth Meyer to make research, scientific and physical examinations of her painting which had been known as the Isleworth Mona Lisa.
In 2010, he formed, together with Markus Frey, Daniel Kohler and others, The Mona Lisa Foundation, a non-profit organisation, which absorbed decades of previous research concerning that painting, and initiated new expertises, scientific tests and physical examinations.