What defines a spot commodity index?

A spot commodity index is defined primarily by its focus on the current prices of the underlying commodities. This index reflects price changes in the actual commodities at the current market prices, rather than relying on futures contracts or other financial instruments that may represent future expectations of prices.

In this context, the correct option emphasizes that spot commodity indices are based solely on the changes in the prices of the commodities themselves. This approach captures the direct market value at any point in time, allowing investors to understand the immediate performance of the commodities without the influence of factors such as futures rollovers or additional costs.

Other options may incorporate various aspects of commodity trading or investment but do not accurately encapsulate the essence of a spot commodity index as it specifically pertains to the current prices rather than the complexities of futures contracts, dividends from stocks, or roll returns. These elements may be relevant in broader discussions of commodities, but they diverge from the fundamental definition that prioritizes spot market price fluctuations.