“…Previous research on the oil industry has investigated long-memory properties in the case of oil consumption (Mohn and Osmundsen, 2008;Lean and Smyth, 2009), returns on oil investment (Boone, 2001) and oil exhaustion (Karbassi et al 2007;Tsoskounoglou et al 2008;Höök and Aleklett, 2008), and energy prices (Serletis, 1992;Lien and Root, 1999;Elder and Serletis, 2008;Kang et al, 2009). However, there are no existing studies on the degree of persistence of energy prices also allowing for possible breaks in the data.…”