Abu Dhabi's stock market fell on Thursday, weighed down by its biggest lender amid global trade tensions and falling oil prices, which sent all major Gulf markets sliding.

Oil prices dropped on Thursday over the escalating trade battle between the United States and China.

The Abu Dhabi index fell 1.3 percent, declining for the sixth straight session, with First Abu Dhabi Bank shedding 1.9 percent and Abu Dhabi Commercial Bank decreasing 2.3 percent.

ADCB, which formalised a merger with two other lenders last week, has been falling since it posted a 5 percent drop in first-quarter profit last week, blaming lower interest income and higher cost of funds.

Investment firm Waha Capital rose 1.9 percent following a Reuters report on Wednesday that it had held exploratory merger discussions with peer Gulf Capital.

Saudi's index was down 0.1 percent with Dar Al Arkan Real Estate Development decreasing 2.1 percent after reporting a drop in first-quarter profit due to lower property sales.

Middle East Healthcare plunged 9.9 percent after it reported a 83 percent slump in its first-quarter profit and its board decided against a dividend payout for 2018.

Separately, Saudi mall operator Arabian Centres is set to raise as much as 2.8 billion riyals ($747 million) after pricing its initial public offering at the bottom of its indicative range, according to a company document.

Qatar's index was down 0.9 percent with heavyweight stocks Qatar National Bank and Industries Qatar falling 2.7 percent and 1.1 percent, respectively.

In Dubai, the index lost 0.6 percent with Deyaar Development trading 2.3 percent lower. The real estate developer said last week that its first-quarter net profit more than halved.

Dubai's Nasdaq-listed DP World, one of the world's largest port operators, slid 1.9 percent. The firm agreed to buy Canadian marine terminal Fraser Surrey Docks from a Macquarie Group fund. ($1 = 3.7503 riyals)

(Reporting by Shakeel Ahmad in Bengaluru; Editing by Jon Boyle) ((shakeel.ahmad.thomsonreuters.com@reuters.net;))