DUBAI — Most stock markets in the Gulf fell on Monday after oil prices sank to new lows and Dubai's index dropped as investors dumped shares in Emaar Properties , which had gone ex-dividend. Dubai's bourse fell 3.3 percent to 4,031 points and Emaar tumbled 7.0 percent late in the session to 8.32 dirhams; both hit five-month lows. Saudi Arabia's index fell 1.7 percent as nearly all stocks in the key petrochemical and banking sectors declined. Saudi Basic Industries dropped 3.0 percent and its subsidiary Yanbu National Petrochemical Co (Yansab), which last week proposed a dividend cut and announced plans to shut down a plant for maintenance, fell 1.3 percent. Brent crude oil fell more than $2 a barrel on Monday to a new five-year low on predictions that oversupply would keep building until next year after OPEC decided not to cut output. Abu Dhabi's bourse was mixed and its main index fell 0.9 percent. Oman's bourse stabilized and inched up 0.1 percent after tumbling 4.2 percent in the previous session. Banking stocks, which had dropped when rating agency Standard & Poor's cut its outlook for Oman's credit rating to negative, rebounded with HSBC Oman and Ahli Bank up 4.5 and 2.0 percent respectively. — SG/Reuters