* Abu Dhabi's TAQA hits 40-month high
* First Abu Dhabi Bank also surges
* Saudi Arabia extends rebound after profit-taking
* QNB, Commercial Bank up as Qatar gains
* Emirates NBD drags Dubai down
By Tom Arnold
DUBAI, April 5 (Reuters) - Abu Dhabi outperformed among mixed regional stock markets on Thursday, with Saudi Arabia extending a rebound following several days of profit-taking.
The Abu Dhabi index closed 1.7 percent higher, supported by the financial and energy sectors. Abu Dhabi National Energy Co (TAQA) (TAQA) jumped 5.9 percent to a 40-month closing high and was the most heavily traded stock.
After several years of struggling with low oil prices, the company's earnings have started to improve and last month, the Abu Dhabi government folded TAQA's parent, utility Abu Dhabi Water & Electricity Authority, into its newly established department of energy - a move which could benefit the company.
First Abu Dhabi Bank, the biggest bank, surged 3.8 percent.
In Saudi Arabia, buyers continued returning to the market for a second straight day following a sell-off of several days when investors booked profits in the wake of FTSE Russell's decision to upgrade Riyadh to emerging market status.
The Saudi index closed 1.0 percent higher, with blue chips Al Rajhi Bank and Saudi Basic Industries rising 2.3 and 2.1 percent respectively.
"Looking ahead, we expect to see the level of inflows ... seen so far in 2018 continue, especially as the likelihood of Saudi Arabia's inclusion into the MSCI EM (emerging markets) index has been greatly increased following the FTSE EM inclusion," Fahad Alturki, head of research at Jadwa Investment, said in a note.
A decision on Saudi Arabia's inclusion in the MSCI emerging markets index is expected in June.
The Qatari index was the other big climber, closing 1.0 percent up. Banking stocks led gains with heavyweight Commercial Bank finishing 3.9 percent up and Qatar National Bank rising 2.6 percent.
Dubai's index dropped 0.3 percent in its fourth straight day of declines. Emirates NBD was the main drag on the index, tumbling 3.3 percent as it went ex-dividend. Emaar Properties slipped 0.5 percent as worries continued about the outlook for the property market.
Egypt's index fell 0.6 percent. Real estate developer Talaat Mostafa, which had soared in recent days to its highest level since the company was listed in November 2007, last traded 10 percent lower in heavy volume.
* The index rose 1.0 percent to 7,953 points.
* The index dropped 0.3 percent to 3,083 points.
* The index rose 1.7 percent to 4,689 points.
* The index gained 1.0 percent to 8,793 points.
* The index fell 0.6 percent to 17,411 points.
* The index fell 0.1 percent to 4,794 points.
* The index was flat at 1,283 points.
* The index edged up 0.1 percent to 4,799 points. (Editing by Andrew Torchia and Alison Williams)