What the spread reveals about the equity-oil link
When the two lines move together, oil is being driven by the same demand conditions that lift equities, the pattern that dominated the 2003-2008 commodity supercycle. When they decouple, with oil falling while equities rise or vice versa, the move is usually oil-specific: a supply shock (positive or negative), an OPEC decision or a storage crisis. The post-2014 window shows almost complete decoupling, with equities climbing while oil traded in a wide range.