Creo que debe ser una información dificil de encontrar. Por un libro que estoy leyendo, por ejemplo para el acero no se creó un precio spot hasta 2003. Incluso para una commodity tan masiva como el crudo, el precio spot es relativamente reciente:
For many commodities, physical markets determined by the interaction of supply and demand are, perhaps surprisingly, a relatively new innovation. Take the most important commodity of all – oil. Prior to the early 1970s, only approximately 5% of the world’s oil was freely traded, whereas the other 95% was determined by long-term contracts with fixed prices.[148]
Meanwhile, up until 2003, iron ore prices were also based on long-term contracts between the largest iron ore miners and Japanese steelmakers. However, as China became an increasing presence in the iron ore market, the big miners abandoned long-term contracts and began to sell their ore on short-term contracts based on prices set on a nascent spot market (see Chapter 11 on ferrous metals).
Despite how it might appear though, most commodity prices are actually very difficult to find. It’s easy, I hear you say, just look on the internet for the latest price for a barrel of Brent crude oil or a tonne of copper. However, the prices quoted in the newspaper or online tend to be for the nearest dated futures contract for a particular commodity, rather than the price at which actual buyers and sellers traded at in the spot market. In reality, the prices of most commodities actually used to produce stuff in the real world are merely estimates based on incomplete information in the physical OTC markets. Commodity prices are generally discovered through a process of interpreting what sources (buyers and sellers) in a particular commodity market say on bids, offers and deals, whilst also accounting for other factors like shipping costs, the size of the deal that took place and a whole host of other factors. These prices are then published by price reporting agencies. With some industry estimates suggesting that as much as 80% of all crude and oil product transactions are linked to reference prices, their accuracy is therefore essential.[149]
Sainsbury, Peter. Commodities 50 Things You Need To Know (pp. 222-223). Edición de Kindle.