Abu Dhabi stocks held near record highs on Monday, extending gains for a sixth consecutive session supported by gains in International Holding (IHC), which continued its rally following the listing of a subsidiary.
IHC's market capitalisation hit 201.7 billion dirhams ($55 billion) last week, making it Abu Dhabi's most valuable listed company, after the market debut of Alpha Dhabi, in which IHC holds a 45% stake.
In Abu Dhabi, the index gained 0.7%, with International Holding gaining 0.4%, while Gulf Pharmaceutical Industries (Julphar) jumped about 7%.
Last week, Abu Dhabi Securities Exchange said there was no maximum ownership limit for non-UAE nationals in the pharmaceutical firm.
Saudi Arabia's benchmark index lost 0.3%, hit by a 1.8% fall in Saudi Telecom and a 0.4% decrease in Al Rajhi Bank.
GCC markets are expected to slide in the coming days as fears over a wider spread of the Delta variant of coronavirus impacts investors' forecasts, said Michael Stark, market analyst at brokerage Exness.
"This should add to the current concerns over a possible slower economic recovery and anticipations over tighter restrictions that would slow the economic recovery."
The main index in Qatar fell 0.3% as most of its stocks were in negative territory, including the Gulf's biggest lender Qatar National Bank, which was down 0.6%.
Dubai's main share index, however, reversed its earlier losses to close flat.
The Dubai market may see some price corrections as its economy is the most dependent on external factors. The Emirates could also be affected further if other countries follow Saudi Arabia's decision in suspending flights to the regional hub, said Stark.
Saudi Arabia has restricted travel to and entry from UAE and three other countries over coronavirus concerns.
Outside the Gulf, Egypt's blue-chip index was flat, as gains in financial stocks were offset by declines among other stocks.