Keynes and the Interwar Commodity Option Market

In the first quarter of the twentieth century, options began to be widely employed in the main financial centres in Europe and the USA for trading in spot and futures markets. From 1921 onward, Keynes embarked upon investment in these derivatives mainly—but not exclusively—in the commodity markets, showing a true fascination for this method of speculation. This type of financial investment he pursued mainly in the 1920s, with only a few operations undertaken during the 1930s. The option markets in which Keynes traded were metals—in particular copper, lead, spelter and, especially, tin. Besides metals, Keynes dealt in options also in other commodity markets, such as rubber and linseed oil, and sparingly in ordinary stocks and government securities. In this paper we offer a reconstruction of Keynes’s speculative activity in commodity options, drawing on the archival material kept in the Keynes Papers held at King’s College, Cambridge. This reconstruction is, to the best of our knowledge, entirely new to the literature and aims to provide an analysis of this particular aspect of Keynes’s investment behaviour, investigating his capacity to predict market trends and offering a preliminary assessment of his performance.