Index investment in commodities markets since the early 2000s led to increased price correlations among different commodities in the US, especially in popular indices like GSCI and DJ-UBS. This financialization process explains why various commodities experienced synchronized price booms and busts in the US from 2006 to 2008. Interestingly, China did not show the same commodity price movements, indicating that emerging economies' growing demands were not the main driver of these price changes.