Saudi shares retreated for a second straight session on Wednesday, tracking weaker oil prices, while some markets cheered Britain's approval of Pfizer's COVID-19 vaccine, which raised hopes of a faster-than-expected global economic recovery.

Britain became the West's first country to formally endorse a jab it said should reach the most vulnerable people early next week. 

However, oil prices slipped as the market awaited a pact from producers on output. Crude prices were hit by a surprise build in oil inventories in the United States and as OPEC and its allies created uncertainty with a two-day delay to a formal meeting to decide whether to increase production in January. 

The Saudi benchmark, which clocked its best monthly gain in four years in November, retreated 0.3%.

Food processing company Anaam International Holdings Group Co was the biggest percentage loser on the Saudi blue-chip index, falling 9.9%, while lender Riyad Bank was down more than 1%.

The Dubai and Abu Dhabi markets are shut for three days for holidays until the end of this trading week and will reopen on Sunday.

In Qatar, the benchmark closed the session almost flat. Qatar Gas Transport Nakilat Co and food processing firm Baladna were among the top gainers, up 1.6% and 4.8% respectively.

Among decliners, Qatar National Bank shed 1.6%, the top loser on the index.

The Kuwait benchmark strengthened more than 1%, with logistics company Agility Public Warehousing Co leading gains by adding 2.8%. Finance stock Ahli United rose more than 2%.

Bahrain's benchmark rose 0.8%, boosted by a 6.5% gain in Aluminium Bahrain.

Outside the Gulf, Egypt's main index eased about 0.2%.

The country's largest dairy products and juices producer Juhayna Food Industries  finished nearly 7% lower after its chairman Safwan Thabet was arrested on Monday pending an investigation. The reasons behind the arrest were unknown to the company, it said. 

(Reporting by Aby Jose Koilparambil in Bengaluru; Editing by Kirsten Donovan) ((abyjose.koilparambil@thomsonreuters.com; +91 (0)8061822683;))