UPDATE 8: Emaar down 5.1%, while Saudi's index closes lower for fourth session running.
Dubai's index made its largest one-day loss in three weeks, with volumes rising by more than a third from the day before, indicating increasing selling pressure.
"In Dubai, we haven't had any strong positive leads to distract us from the concerns that are out there such as Dubai World's restructuring," said Ali Khan, managing director and head of brokerage at Arqaam Capital.
Emaar Properties fell 5.1 percent, slumping to a four week low, while Arabtec declined for a fourth day since agreeing a stake sale to Aabar Investments that will dilute existing shareholdings.
Dubai's index fell 2.7 percent to 1,712 points, a four-week low.
Dubai World stunned global markets in late November by asking for a standstill as it tries to restructure billions of dollars of debts.
Aldar Properties slumped to a four-week closing low, dragging Abu Dhabi's index to its biggest one-day loss since December 23.
Aldar dropped 5.4 percent and rival Sorouh Real Estate fell 4 percent as investors dump UAE property stocks. RAK Properties dropped 3.5 percent, with this trio accounting for about half of all shares changing hands on the index.
Aabar Investments, which is set to buy a majority stake in Dubai-listed Arabtec, fell 3.2 percent.
The index dropped 1.6 percent to 2,714 points as losers outnumbered gainers 28 to one, tracking declines on Dubai's benchmark.
"Dubai's debts will remain an overhang for the rest of the Gulf," said a Kuwait-based trader who asked not to be identified.
"Foreign investors are exiting the UAE and looking to get into Qatar and that will be a theme over the next few months." Saudi Arabia's index ended lower for a fourth session following late selling pressure, but Saudi Basic Industries Corp (SABIC) hit a 14-month high as investors bet its earnings will beat estimates.
Riyad Bank fell 2.3 percent, but Saudi Hollandi Bank and Banque Saudi Fransi edged higher after falling for the previous two sessions following below-forecast earnings from the two lenders.
SABIC rose 1.4 percent to a 14-month high.
Kingdom Holding rose 8 percent, rallying for a second day since its major shareholder gave a bullish outlook for the troubled firm.
The index eased 0.1 percent to 6,263 points.
Kuwait's index ended lower for a third day, with volumes falling by more than half from the day before as investors sat out the market until the big names report earnings.
"Volumes are so low -- most investors are waiting for banks to announce their results -- Saudi banks' performance has got everybody worried," said a Kuwait-based trader who asked not to be identified.
"We're not correlated to the Saudi market, but if Saudi banks are doing badly then Kuwait's are likely to as well.
"National Bank of Kuwaitis likely to be the first to announce and that will set the tone for the wider market."
Qatar National Bank ended lower despite reporting a rise in quarterly profit, weighing on Doha's index, which hit a six-week low as a pull-back in regional and global stocks weighed on sentiment.
QNB slipped 1.3 percent. The lender's fourth-quarter profit rose 65 percent.
Other banks also slid as poor earnings from Saudi banks dampened expectations for the sector.
Commercial Bank of Qatar dropped 1.5 percent and Masraf Al Rayan lost 0.8 percent. The longer-term outlook is healthier, with Qatar remaining a top pick for regional investors.
The index fell 1.1 percent to 6,834 points, its fourth straight decline and lowest finish since December 1.
Heavyweight Industries Qatar dropped 1.7 percent, with declining oil prices likely to dampen appetite for the petrochemicals producer.
Bahrain's measure ended almost unchanged, edging up 0.01 percent to 1,475 points. (Reuters)