DUBAI, April 20 (Reuters) - Petrochemical shares were the main drag on Saudi Arabia's stock market in early trade on Thursday after oil prices fell sharply overnight, while Qatar's index was hit by weak earnings from oil rig provider Gulf International Services.
The Saudi index was down 0.5 percent after half an hour of trade as almost three-quarters of listed petrochemical shares fell, with heavyweight Saudi Basic Industries dropping 0.5 percent.
Most petrochemical producers have not yet reported first-quarter earnings. Companies in Saudi Arabia are now obliged to report earnings based on IFRS standards, and the securities regulator said last year that firms could report interim earnings as long as 30 days after the end of each period, rather than 15 days as previously.
Most Saudi banking shares also fell with Saudi Investment Bank, the worst performer, down 1.2 percent. All Saudi banks, except for Samba Financial Group, have reported earnings; while results were mixed, most beat expectations.
Cement shares slipped with Qassim Cement, the latest in the sector to report a slump in first-quarter earnings, down 0.6 percent. It reported a net profit of 80.3 million riyals ($21 million), down 40 percent from a year ago.
In Doha, Gulf International Services dropped 5.3 percent after it reported an 81 percent slide in first-quarter earnings to 15 million riyals ($4.1 million), far below QNB Financial's forecast of 452 million riyals and Alphamena's estimate of 378 million riyals.
The Qatari stock index was down 0.9 percent.
In Abu Dhabi, First Abu Dhabi Bank, formed on April 1 by the merger of National Bank of Abu Dhabi and First Gulf Bank, rose 0.5 percent after it announced a 12.4 percent rise in combined "pro-forma" first quarter net profit to 2.93 billion dirhams ($798 million).
That was aided by a 145.5 percent jump in "other non-interest" income while loan impairment charges slipped 3.9 percent. The merger is expected to produce cost savings of 500 million dirhams, the bank said.
Abu Dhabi National Energy Co jumped 5.4 percent after its chief operating officer told Reuters on Wednesday it might sell some oil and gas interests in North America to raise capital for its core business.
Earlier this month TAQA said the state-owned utility had raised its stake in the company to 74 percent from 52.38 percent after granting TAQA land valued at 18.7 billion dirhams that could potentially offset accumulated losses.
Profit taking on other shares, however, weighed on the Abu Dhabi index, which fell 0.3 percent. Aldar Properties retreated 2.3 percent.
In Dubai, the index was down 0.8 percent as builder Arabtec, which had jumped almost 11 percent on Wednesday after shareholders approved its 1.5 billion dirham new share issue and a plan to use existing capital to wipe out accumulated losses, fell 2.3 percent. (Reporting by Celine Aswad; Editing by Andrew Torchia and Susan Fenton)