This paper develops a theory of the precautionary demand for commodity stocks. It suggests that commodity stocks are held for precautionary purposes by producers, consumers, and intermediate processors, while speculators hold stocks on the expectation of capital gains from a subsequent price rise. Producer and consumer stocks usually account for the largest share of commercial stocks held at any point in time. For example, at the end of 1990, stocks held by producers and consumers of copper were 72 percent of all commercial stocks of the market economy countries. Yet, the theory explaining the behavior of this class of stocks has not progressed much beyond the concept of convenience yield, first introduced by Kaldor (1939). This paper proposes an alternative theory. Holding of stocks by producers and consumers is viewed as precautionary behavior towards output and price risks. As a theory of behavior towards risks, the precautionary stock demand model encompasses speculative demand by both producers and consumers. Furthermore, both stocks and futures are treated as precautionary instruments, in contrast to the dichotomy that only stocks provide convenience yield while futures are hedging instruments.
