* Investors dump Emaar after securing dividend payout
* Dubai's index drops to five-month low
* But Air Arabia rises, set to benefit from cheap oil
* Oman's bourse stabilises after sharp drop
* Egypt extends gains on positive news flow
By Olzhas Auyezov
DUBAI, Dec 8 (Reuters) - 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.
While there was no fundamental reason for such a steep drop by Dubai's biggest listed property firm, the most likely explanation was a sell-off by investors who had held it for a dividend payout, said Shakeel Sarwar, head of asset management at Securities & Investment Co in Bahrain.
The record date for Emaar's special 1.257 dirham dividend was Nov. 30 and the stock has since plunged 21.5 percent. It has major technical support at 7.95 dirhams, the June low.
Most other Dubai stocks also fell, with the exception of low-cost carrier Air Arabia, which jumped 2.0 percent to 1.56 dirhams. The stock has gained 18.2 percent since the end of October, becoming a safe haven in an otherwise bearish market; it faces strong chart resistance at 1.65-1.68 dirhams, this year's peaks.
With fuel making up a significant part of Air Arabia's costs, the company stands to benefit from cheaper oil.
Abu Dhabi's bourse was mixed and its main index fell 0.9 percent. First Gulf Bank and Union National Bank fell 1.1 and 3.8 percent respectively, while National Bank of Abu Dhabi rose 1.6 percent.
Oman's bourse stabilised 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.
However, Raysut Cement, which had fallen its daily 10 percent limit on Sunday, dropped a further 3.2 percent. The firm said on Sunday that the price it paid for gas supplies would double next year, as the government responded to the oil price drop by cutting subsidies.
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. Cheaper oil may eat into the margins of Gulf petrochemical producers, which have previously enjoyed cost advantages thanks to subsidised feedstock.
Oil importer Egypt's stock market rose for a fourth straight session, adding 0.5 percent. Carpet maker Oriental Weavers surged 6.1 percent to 60.00 pounds, its highest level since early 2006.
The company said last week it would launch two new carpet manufacturing plants and one plant to produce threads. The Daily News Egypt newspaper also quoted its founder Mohamed Farid Khamis as saying sales would grow 5.5 percent this year.
Shares in property developer Heliopolis Housing jumped 4.8 percent after its annual meeting approved a dividend of 1.0 pound per share, up from last year's 0.85 pound, according to Reuters data.
* The index dropped 3.3 percent to 4,031 points.
* The index slid 0.9 percent to 4,676 points.
* The index inched up 0.1 percent to 6,308 points.
* The index fell 1.7 percent to 8,786 points.
* The index rose 0.5 percent to 9,578 points.
* The index inched up 0.03 percent to 12,645 points.
* The index fell 1.3 percent to 6,665 points.
* The index slipped 0.1 percent to 1,410 points. (Editing by Andrew Torchia)