* Qatar index stops at major chart barrier on 2008 peak
* Rumours of potential large investments lift Islamic banks
* Dubai, Abu Dhabi rise but remain below this month's peaks
* Ahli United Bank lifts Bahrain's bourse on merger talk
* Saudi's Dar Al Arkan gains after Q1 results beat estimates
By Olzhas Auyezov
DUBAI, April 17 (Reuters) - Qatar's bourse continued to outperform the region on Thursday but failed to break through major technical resistance. Ahli United Bank lifted Bahrain's stock market on news it might be sold or merge.
The Doha bourse closed up 0.8 percent at 12,551 points, retreating from an intra-day peak of 12,679 points, the highest level since September 2005. It faces chart resistance at 12,637 points, its 2008 peak.
Islamic lenders contributed most to the increase: Masraf Al Rayan rose 5.8 percent, Qatar International Islamic Bank added 3.1 percent and Qatar Islamic Bank (QIB) gained 2.7 percent.
The shares rose on speculation that Ezdan Holding Group might look to buy stakes in more sharia-compliant businesses, a fund manager investing in Qatar said.
Last month Ezdan, whose shares jumped their daily limit of 10 percent on Thursday, bought a stake of more than 20 percent in Islamic investment firm Islamic Holding Group. Early this month, The Peninsula newspaper quoted the company's chief executive as saying it would announce big investments in two more listed sharia-compliant companies by June.
Also, QIB reported a 15 percent increase in first-quarter net profit late on Thursday. The bank earned 335 million riyals ($92 million), slightly above the average estimate of eight analysts polled by Reuters who had expected 328 million riyals.
Dubai's index added 0.7 percent to 4,762 points on moderate volume, remaining below this month's peak of 4,840 points.
"It is probably because of a lack of catalysts," Amer Khan, senior executive officer at Shuaa Asset Management, said of the lower trading activity in recent days.
Dubai Islamic Bank contributed most to the move, adding 3.2 percent as the bourse officially raised the cap on foreign ownership of its stock to 25 percent from 15 percent.
Thomson Reuters data shows investors from outside the Gulf increased their holdings to 10.3 percent of shares on Thursday from 10.1 percent on Wednesday while Gulf investors from outside the United Arab Emirates still held 4.8 percent.
Some analysts believe index compiler MSCI will include Dubai Islamic Bank in its emerging market index at the end of May, though it was absent from the provisional list of constituents published last year.
Modest gains posted by most blue chips ahead of first-quarter earnings reports lifted Abu Dhabi's bourse 0.5 percent to 5,157 points, close to the eight-year closing peak of 5,172 points which it hit last Thursday.
Ahli United Bank (AUB), Bahrain's biggest lender, single-handedly lifted the local bourse's index by 0.7 percent. The move came after several bankers familiar with the situation told Reuters on Wednesday that AUB was evaluating a sale or a merger with a rival bank in a potential $5 billion deal.
The bank said on Thursday it could not comment, but the report suggested the possibility of consolidation in the Bahraini banking sector that could benefit the whole industry. The central bank has been encouraging mergers in the sector.
AUB shares listed on the Bahrain stock exchange jumped 3.2 percent; the shares cross-listed in Kuwait were up 0.9 percent. Shares in the bank's Kuwaiti subsidiary rose 1.5 percent.
Saudi Arabia's bourse added 0.3 percent. Property developer Dar Al Arkan jumped 3.5 percent after it reported a 4.3 percent increase in first-quarter net profit on Thursday, beating analysts' forecasts.
The kingdom's largest listed property developer made a net profit of 247.9 million riyals ($66.1 million) in the quarter while three analysts polled by Reuters had expected, on average, a profit of 222.3 million riyals.
* The index rose 0.8 percent to 12,551 points.
* The index gained 0.7 percent to 4,762 points.
* The index climbed 0.5 percent to 5,157 points.
* The index added 0.3 percent to 9,531 points.
* The index rose 0.3 percent to 8,104 points.
* The index slid 0.9 percent to 7,451 points.
* The index rose 0.7 percent to 1,389 points.
* The index added 0.3 percent to 6,844 points. ($1 = 3.7503 Saudi Riyals) (Editing by Andrew Torchia)