By Dylan Bowman
Doha's index makes it six gains in a row, while Muscat's breaks two-day slump.
Qatar closed up for a six consecutive session on Tuesday as banking stocks pushed the main index up almost half a percentage point.
Elsewhere in the Oman got back to wining ways, along with Abu Dhabi and Kuwait, while Dubai, Saudi Arabia and Bahrain all finished the day in the red.
Qatar's gains were paced by Qatar Islamic Bank (QIB) and Qatar National Bank (QNB). QIB and QNB gained 4.14 percent and 1.74 percent respectively, boosting the index to close up 0.46 percent at 12,513.65 points.
Qatar is the second-best performer in the Gulf Arab region so far this year.
Oman's benchmark ended higher after two days of losses, helped by gains in Oman Telecommunications Co. (Omantel) and Raysut Cement Co.
Omantel and Raysut rose 2.59 percent and 1.14 percent respectively, leading the benchmark to close up 0.49 percent at 12,000.65 points.
The measure is the best performer in the region as it is up more than 32 percent this year to Tuesday's close.
In Abu Dhabi shares of Abu Dhabi National Energy Co. (Taqa) climbed 3.99 percent after the firm's board agreed to sell 4.15 billion dirhams ($1.13 billion) worth of bonds convertible into shares.
The UAE capital's index edged up 0.35 percent to 5,125.89 points.
Kuwait's benchmark ended up 0.3 percent at 15,354.70 points. National Industries Group and Commercial Bank of Kuwait (CBK) drove the gains, rising 2.99 percent and 1.35 percent respectively.
Dubai's main index lost more than 1 percent, led by declines in Emirates NBD and Emaar Properties.
Emirates NBD and Emaar declined 2.47 percent and 1.72 percent respectively, dragging the benchmark 1.18 percent lower to 5,726.66 points.
Saudi Arabia's main index closed lower for the second time in five sessions, weighed by declines in shares of Saudi Basic Industries Corp. (SABIC) and Banque Saudi Fransi.
SABIC and Saudi Fransi fell 1.17 percent and 2.99 percent respectively, dragging the benchmark down 0.11 percent to 9,766.37 points.
The index is the worst performer in the Gulf Arab region as it is down more than 11 percent this year to Tuesday's close.
In Bahrain Gulf Finance House declined 2.49 percent, pulling the benchmark down 0.21 percent to 2,881.58 points.