“…However, commodities are not only simple inputs, they are also investment assets that are in the middle of attention of numerous retail as well as institutional investors. This is why commodity markets and various factors affecting commodity prices are studied by many economists (Androniceanu, & Popescu, 2017;Balaz, & Zabojnik, 2010;Burciu, 2017;Dudzinski, 2010;Back et al, 2013;Smiech et al, 2015;Vychytilova, 2015;Han et al, 2016;Karyotis, & Alijani, 2016;Bianchi et al, 2016;Huchet & Fam, 2016;Ntananamis, & Zhou, 2016;Pirrong, 2017;Ghoddusi, & Emamzadehfard, 2017;Olah el al., 2017 etc. ;Simionescu, 2017;Vovk, I., Vovk, Y., & Lyashuk, O., 2017).…”