Trading in the “Devil’s metal”: Keynes’s speculation and investment in tin (1921–1946)

In a recent paper, Alessandro Roncaglia, reconstructing the long- term developments and structure of the oil markets, noted that this “industry is complex, with production stages that are technically quite different from one another[; …] it is characterised by strong economic and political interests intertwined in an interplay of conflicts and alliances that evolve over time, while technology, the organization of the markets and their size also dramatically change” (2015, 151). This also applies to tin, a commodity whose characteristics made it an object of several cartels dominated by intertwined national and private interests, marked by high price volatility, control of which was pursued by various forms of international agreements, with or without the support of buffer stocks, from the 1920s to the 1980s. Tin was also the commodity that John Maynard Keynes dedicated most attention to as speculator, investor and commentator. It was probably the commodity in which he invested most, together with cotton and wheat, and where he suffered the greatest losses, alongside rubber. His trading in tin spanned from 1921, when he first bought a future contract, until his death in 1946. In this chapter, we present a reconstruction of Keynes’s dealings in tin, as economist, speculator and investor, taken as a lens through which to examine the tin market in the interwar period.