In Kuwait, the index slid 3% as all its constituents ended in negative territory, including Kuwait Projects Company, which was down 2%.
Kuwait's 91-year-old ruler Emir Sheikh Sabah al-Ahmad al-Sabah was admitted to hospital on Saturday for medical checks and underwent successful surgery on Sunday morning.
His office, in a statement carried by state news agency KUNA, did not specify what kind of surgery he had.
Dubai's main share index dropped 1.1%, with blue-chip developer Emaar Properties shedding 2.2% and its unit Emaar Malls losing 2.8%.
Elsewhere, Emirates NBD Bank retreated 1.5%.
In Abu Dhabi, the index edged up 0.1%, helped by a 1.9% rise in Emirates Telecommunication Group (Etisalat).
The telecoms company reported an increase in second-quarter net profit.
The Qatari index slipped 0.1%, hit by a 1.9% fall in Qatar Insurance Company and a 0.4% drop in Qatar Islamic Bank.
Separately, Qatar Airways is seeking at least $5 billion in compensation from Saudi Arabia, the United Arab Emirates, Egypt and Bahrain for blocking it from their airspace, the state-owned carrier said on Wednesday.
Outside the Gulf, Egypt's blue-chip index fell 0.9%, with Commercial International Bank declining 2.2%.
Egypt's economic growth will slow to 3.1% in the fiscal year 2020/2021 that began this month due to the coronavirus pandemic, a Reuters poll showed on Tuesday, down from 3.5% forecast in a similar poll three months ago.
SAUDI ARABIA rose 0.1% to 7,428 points ABU DHABI added 0.1% to 4,262 points DUBAI 1.1% to 2,065 points QATAR slid 0.1% to 10,295 points EGYPT down 0.9% to 10,460 points BAHRAIN dropped 0.8% to 1,293 points OMAN gained 1.3% to 3,522 points KUWAIT was down 3% at 5,260 points
($1 = 3.6728 UAE dirham)
($1 = 3.7501 riyals)
(Reporting by Ateeq Shariff in Bengaluru. Editing by Jane Merriman) ((AteeqUr.Shariff@thomsonreuters.com; +918061822788;))