* Qatar's Commercial Bank jumps on Q1 earnings beat
* PetroRabigh leaps in Saudi Arabia
* Zain Saudi rises in heaviest trade for a year
* Emaar Properties drags down Dubai again
* Egypt's Pioneers Holding plunges on capital increase plan
By Andrew Torchia
DUBAI, April 18 (Reuters) - Stock markets in Qatar and Saudi Arabia climbed on Wednesday while the rest of the region was sluggish, with a slide in Dubai blue chip Emaar Properties dragging down that market once again.
The Qatari index surged 1.1 percent as Commercial Bank gained 3.8 percent. It reported a 345 percent year-on-year jump in first-quarter net profit to 405 million riyals ($111 million). The average forecast from analysts polled by Reuters was 329.5 million riyals.
Doha Bank, which is to announce its first-quarter earnings next Sunday, climbed 3.4 percent. Qatari banks' earnings so far in the reporting season have generally been strong, suggesting the impact on them of the embargo imposed by other Arab states on Qatar has largely faded.
In Saudi Arabia, the index gained 0.6 percent, rising for a fifth straight day. The market is bullish because of expectations for foreign fund inflows in the coming two years as the kingdom joins emerging market indexes.
PetroRabigh was the biggest gainer, surging 7.9 percent to its highest level since October 2014. It will go ex-dividend next Wednesday. With a trailing price-earnings ratio of about 17 times and a dividend yield of 1.8 percent, the stock is no longer cheap by some measures.
"The anticipated fund flows are large so a lot of stocks are just moving on momentum now," said one Saudi fund manager, adding that even though many valuations were looking rich, the market might still have the energy to rise further.
Telecommunications firm Zain Saudi closed 3.6 percent higher in its heaviest trade since April 2017, although it came well off its intra-day high.
Dubai's index sank 1.4 percent as Emaar Properties slipped 3.6 percent. The stock has been dragged down this year by the weakness of the Dubai real estate market.
Strong bank earnings failed to boost stocks. Dubai Islamic Bank dropped 1.8 percent after reporting a 17 percent rise in quarterly net profit, while the biggest bank, Emirates , fell 0.5 percent despite posting a 27 percent increase in quarterly profit that beat analysts' estimates.
In Egypt, the blue chip index slid 0.5 percent as major financial services firm Pioneers Holding plunged 10 percent to 9.58 Egyptian pounds after saying it would increase its capital by 30 percent. New shares will be sold to existing shareholders at 5 pounds per share.
** The index rose 0.6 percent to 8,146 points.
** The index fell 1.4 percent to 3,088 points.
** The index dropped 0.5 percent to 4,682 points.
** The index surged 1.1 percent to 9.055 points.
** The index fell 0.5 percent to 17,706 points.
** Kuwait edged down 0.1 percent to 4,778 points.
** The index dropped 0.4 percent to 4,752 points.
** The index was flat at 1,302 points. (Reporting by Andrew Torchia; Editing by Jon Boyle)