According to the principle of microeconomics, when the supply of a commodity exceeds the demand, its price falls, and vice versa. At the same time, price will affect supply and demand in turn, that is, when the price rises, supply will increase and demand will decrease, on the contrary, demand will increase and supply will decrease, so price and supply and demand are interactive.

An important indicator reflecting the relationship between supply and demand is inventory. The inventory of copper is divided into reported inventory and non-reported inventory. Stock reporting, also known as "visible stock", refers to the stock of the exchange. At present, London Metal Exchange (LME), Comex Branch of the New York Mercantile Exchange (NYMEX) and Shanghai Futures Exchange (SHFE) are internationally influential copper futures trading institutions. All three exchanges regularly publish the inventory of designated warehouses.

Unreported stocks, also known as "invisible stocks", refer to stocks held by manufacturers, traders and consumers all over the world. Because these stocks are published irregularly, it is difficult to count them, so they are generally measured by exchange stocks.