By Nadia Saleem

DUBAI, Nov 12 (Reuters) - Shares in Abu Dhabi made their biggest one-day gain in nine months on Monday, while most other Gulf stock indexes slipped as investors booked gains against a weak global backdrop.

Abu Dhabi's main market index .ADI finished 1.3 percent higher, its largest daily rise since Jan. 31. Banks helped lift the benchmark, which closed at a level last seen in July 2011.

National Bank of Abu Dhabi NBAD.AD (NBD) rose 3.4 percent to 9.81 dirhams, extending this year's gains to 23.2 percent. Abu Dhabi Commercial Bank ADCB.AD climbed 1.5 percent, while First Gulf Bank FGB.AD (FGB) ended flat, having gained 37.4 percent so far in 2012.

Banks have in the last couple of weeks posted strong growth in quarterly earnings, with NBAD and FGB beating analysts' estimates for the three months to Sept. 30. ID:nL5E8LN82I

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Traders said there did not appear to be any fresh news event behind Monday's rally, but that retail investors poured money into banks to try to ride the momentum.

"If you look at UAE banks in general, what people are looking for is credit quality and asset expansion - NBAD has the lowest non-performing loan ratio and FGB is in the top of its class in asset expansion," said an Abu Dhabi-based trader who asked not to be identified.

But Nabil Al Rantisi, managing director at Menacorp in Abu Dhabi, said NBAD and FGB had already priced in the bullishness of investors.

"NBAD is at a critical area, and cooling down a bit is the most likely scenario for now - a retracement back to the 9 (dirham) level is something that will happen in the short term.

"A retracement before continuing upwards is the most likely scenario, as the general outlook on the UAE equity markets remains bullish," Al Rantisi added.

Index heavyweight Etisalat ETEL.AD rose 2.3 percent while some small-caps gained in heavy trade, boosted by speculative buying by retail investors. Eshraq Properties ESHR.AD and Green Crescent Insurance Co GCIC.AD jumped 9.7 and 9.1 percent respectively.

Dubai's Gulf General Investment Co GGIC.DU soared 8.4 percent helping the Dubai index .DFMGI climb 0.8 percent to finish at its highest close since Oct. 24.

SAUDI SLIPS

In Saudi Arabia, however, the bourse slipped for a third straight session from Wednesday's six-week high, closing 0.8 percent lower.

Most sectors in the kingdom fell with turnover the highest in insurance stocks. The sector's index .SINSI dropped 0.9 percent.

"This is mostly investors adjusting positions and some booking profits," said Faisal Al-Othman, portfolio manager at Riyadh-based Arab National Bank, suggesting the market would stay broadly flat through the end of this year.

Global share markets edged down for a fourth day on Monday as concerns about a potential U.S. fiscal crisis and Greece's bailout dented optimism over global growth. MKTS/GLOB

Elsewhere in the Gulf, Qatar's benchmark .QSI dropped 0.4 percent to its lowest finish since Oct. 14. A lack of catalysts as well as the global environment spurred investors to cut positions.

In Kuwait, the index .KWSE ticked up 0.03 percent to a near three-week high, holding on to gains that began after comments by the Emir last week. He said he would "deal with all problems" related to economic development and political stability, though he did not give details of his plans.

Analysts said activity by state-linked funds was helping to lift the market. ID:nL5E8MB3O6

In Oman, Renaissance Services RSC.OM tumbled 9.3 percent, the main drag on the market. Investors were disappointed with the engineering and marine firm's third-quarter earnings. It posted a 37 percent fall in third-quarter net profit before minorities. ID:nL5E8MC1MX

The company also said its engineering group recorded an operating loss of 6.6 million rials for the first nine months of the year, against a 5.1 million rial loss in the corresponding period of 2011. It cited unrpofitable contracts.

"With the turnaround in business delivery we are confident the negative impact of engineering shall not reccur in 2013," it said in a statement.

Muscat's index .MSI fell 0.9 percent to its lowest close since Oct. 24.

MONDAY'S HIGHLIGHTS

ABU DHABI

* Market index .ADI rose 1.3 percent to 2,705 points.

DUBAI

* Market index .DFMGI gained 0.8 percent to 1,626 points.

SAUDI ARABIA

* Market index .TASI fell 0.8 percent to 6,830 points.

QATAR

* Market index .QSI declined 0.4 percent to 8,494 points.

KUWAIT

* Market index .KWSE ticked up 0.03 percent to 5,787 points.

OMAN

* Market index .MSI dropped 0.9 percent to 5,655 points.

BAHRAIN

* Market index .BAX slipped 0.4 percent to 1,063 points.

(Editing by Andrew Torchia)

((nadia.saleem@thomsonreuters.com)(+97143664256)(Reuters Messaging: nadia.saleem.thomsonreuteres@reuters.net))

Keywords: MIDEAST MARKETS/