Saudi Arabia's stock market fell on Thursday, reversing most of the previous session's gains made as state-owned oil giant Aramco debuted on the exchange, while other major Gulf markets were also little changed.

Aramco, however, jumped 8.1%, adding to a 10% rise on Wednesday. Its shares had been as much as 10% higher at 38.7 riyals at Thursday's market open, implying a market value of $2 trillion, Refinitiv data showed.

Aramco raised $25.6 billion on Dec. 5 through its IPO and plans to exercise a 15% greenshoe option in whole or part during the first 30 days of trading. If the option is exercised in full, the total raised from the IPO would amount to $29.4 billion.

The firm is expected to be included in the MSCI emerging markets index on Dec. 17.

Saudi's benchmark index fell 0.5%, with a 1.4% drop in Saudi Basic Industries and a 0.5% fall in Al Rajhi Bank dragging, while Saudi Telecom lost 1.4% after JP Morgan cut its target price on the stock to 108 riyals ($28.80) from 111 riyals.

The Abu Dhabi index was 0.2% lower, as market heavyweight First Abu Dhabi Bank eased 0.3% and telecoms firm Etisalat dipped 0.1%.

The Qatari index also fell 0.2%, with the Gulf's largest lender Qatar National Bank down 0.3% and Qatar International Islamic Bank 1.4% lower.

In Dubai, the index was up 0.1%, with blue-chip developer Dubai Islamic Bank rising 0.4% and Dubai Investments 0.8%.

($1 = 3.7500 riyals)

(Reporting by Shamsuddin Mohd in Bengaluru; Editing by Kirsten Donovan) ((shamsuddin.mohd@thomsonreuters.com; +918067497252;))