The aim of this article is to analyse the strategies employed by the Rothschilds up to 1940 to gain control and limit competition in the international non‐ferrous metals markets. It examines how they opted for inelastic demand products of highly concentrated supply which lent themselves to market control (mercury, nickel, lead, and copper and sulphur) by taking administrative monopolies (mercury from the state‐owned Almadén mines in Spain) or by controlling the leading businesses of the respective markets (Le Nickel, Peñarroya, and Rio Tinto). The article also analyses how in some cases the family was able to gain worldwide monopolies, and how in other cases they promoted collusive oligopolies with the competition in any number of forms in their quest to maintain profitability and steer well clear of any competition.