RIYADH: As concerns over the spread of Omicron mounted and investor uncertainty aroused, most of the Gulf Cooperation Council’s stock exchanges ended lower on Monday, including Saudi Arabia. Saudi bourse’s main TASI index edged down slightly to 11,161 points, while the parallel market, Nomu, declined around 1 percent to 26,237 points. The Qatari index, QSI, and Oman’s index,