Most major Gulf stock markets gained on Tuesday, but Saudi Arabia's traded flat with financials and petrochemicals moving sideways.

Saudi's benchmark index was flat, with Riyad Bank shedding 3% and Al Rajhi Bank losing 0.2%.

On Monday, Riyad Bank and National Commercial Bank decided to end preliminary merger talks, the two said in separate stock exchange filings.  NCB was up 0.3%.

Saudi Aramco slipped 0.3% in early trade after four straight days of gains. The state-owned company will join MSCI on Tuesday.

Aramco listed 1.5% of its shares at 32 riyals ($8.53) on the kingdom's Tadawul exchange on Dec. 11 in the world's largest initial public offering (IPO).

Among other stocks, Saudi Bahri advanced 2.8% after it signed a contract with a saline water conversion company to supply desalinated water from floating stations.

Saudi Arabia Fertilizers rose a further 1.1% a day after its board proposed a dividend of 1.5 riyals per share for the second half of 2019.

In Dubai, the index added 0.7%, extending gains for a sixth straight session. Emirates NBD Bank rose1.2% and Dubai Islamic bank was up 0.7%.

The Qatari index added 0.6%, driven by a 1.3% gain in Qatar National Bank and a 1.3% rise in Industries Qatar.

On Monday, Qatar said it plans to spend 1.9% more in 2020 than this year, its biggest budget in five fiscal years. The 210.5 billion Qatari riyal ($57.83 billion) budget will go to complete infrastructure projects, including facilities for soccer's 2022 World Cup.

The Abu Dhabi indexalso inched up 0.1%. Etisalat gained 0.4% and Abu Dhabi National Oil Company for Distribution rose 4.9%.

($1 = 3.6400 Qatar riyals)

($1 = 3.7500 riyals)

(Reporting by Shamsuddin Mohd in Bengaluru, editing by Larry King) ((shamsuddin.mohd@thomsonreuters.com; +918067497252;))