Dubai's index was down 3.3%, with Emaar Properties losing 4.4%
Gulf stock markets fell in early trade on Thursday, hit by oil prices' slide to fresh 11-year lows, a global equities sell-off in response to market turmoil in China, and the prospect of a slowdown in Gulf economies.
Qatar's index sank 2.2 percent to 9,852 points in the opening minutes of trade, approaching technical support on its December low of 9,614 points.
Selling was broad-based, but the biggest losers included oil-related stocks such as drilling rig provider Gulf International Services, which was the most heavily traded stock and tumbled 4.6 percent. Petrochemical producer Industries Qatar lost 3.4 percent.
Dubai's index was down 3.3 percent at 2,970 points after nearly an hour of trade, still testing fresh lows. It has technical support at the December low of 2,851 points. Selling was indiscriminate, with blue chip Emaar Properties losing 4.4 percent.
Abu Dhabi's index, which is usually less liquid and volatile than Dubai, dropped 1.3 percent, with real estate shares leading declines.
Purchasing managers' surveys released on Thursday showed business activity growth in the United Arab Emirates' non-oil private sector slowed to a 40-month low in December. Growth in Saudi Arabia's non-oil private sector slowed to its lowest since the survey began in August 2009.