Why an obscure hydrocarbon may be carrying bad news for the global economy

An obscure product made by oil refineries has a grim story to tell investors right now about the fortunes of the global economy.

That product is naphtha, something used to make a vast array of goods while also being integral to churning out gasoline. Oil refiners’ margins from making it are the weakest in years in Europe and Asia. Unusually, some petrochemical plants in Asia have even been losing money when processing it.

Signs of weakening manufacturing in China could scarcely have come at a worse time for the market, given a backdrop of surging U.S. shale oil and gas