The crash in oil prices in late 2014 and early 2015 challenged long-standing assumptions about the workings of the oil market and prompted a number of tough questions. How will Saudi Arabia respond to low prices? Are US shale producers now setting the marginal price of a barrel of oil? And, above all, has the market reached the bottom yet?
In recent months, as prices have levelled off, some analysts have started asking another intriguing question: are exchange-traded funds (ETFs) propping up the