DUBAI, Sept 20 (Reuters) - Lower crude oil prices and jittery global shares are likely to weigh on investor sentiment on stock markets in the Gulf on Tuesday.

Brent futures were trading at $45.79 a barrel in Asian trade, down roughly 9 percent from its Sept. 8 peak of $50.14.

MSCI's broadest index of Asia-Pacific shares outside Japan slipped 0.2 percent, after major U.S. indexes ended a choppy session nearly flat.

Dubai's index , which has been outperforming peers this week, will likely witness some profit-taking at current levels.

On Monday, Saudi Arabia's index tested a technical support at last month's low of 5,911 points as investors dumped shares across all sectors.

"A combination of factors has contributed to this correction, chief amongst which is investors' concern that corporate earnings for the third quarter could be particularly depressed," said Mohamed Eljamal, the director of capital markets at Abu Dhabi-based Waha Capital.

"Overall market valuations are also continuing to adjust in order to reflect the new earnings norm, corporates are feeling the squeeze both on the revenue side due to softer demand and on the costs side due to subsidy removal."

Twenty-two Qatari listed companies will be added to FTSE's secondary emerging market index on Tuesday, and Doha's share index , which fell 4 percent on Monday, will likely trade lower although the magnitude of decline may be less severe.

"Investors in Qatar can now focus on fundamentals rather than the one-off event now," saia a Dubai-based portfolio manager.



(Reporting by Celine Aswad; Editing by Biju Dwarakanath) ((celine.aswad@thomsonreuters.com)(+9715 62247653)(Reuters Messaging: celine.aswad.thomsonreuters.com@reuters.net))