DUBAI: Dubai's stock market plunged on Sunday as builder Arabtec triggered another sell-off, while investors in Saudi Arabia and Qatar were disappointed by fresh quarterly earnings reports.

The slide in Dubai illustrated the extent to which the market remains dominated by a single stock, its most heavily traded counter in recent weeks, which is prey to wild swings because of frenzied trading by retail investors and short-term speculators.

Arabtec plunged its daily 10 percent limit after Aabar Investments, one of its major shareholders, did not confirm a media report which said Aabar was in talks to increase its stake. Dubai's main index closed 6.0 percent lower.

"It is Arabtec which is affecting the market," said Shakeel Sarwar, head of asset management at Securities and Investment Co. in Bahrain.

"This is crazy volatility...The main issue is that the market does not have depth, it’s totally at the mercy of retail investors and speculators."

Samer Mardini, vice president for fixed income and financial officer at SJS Markets, said speculators "trying to play on Arabtec rumors and news to drive the equity market in their favor" had pushed the market to "a non-rational level".

Arabtec jumped last week on speculation that Aabar would raise its stake from the current 18.94 percent. The bourse suspended the stock on Thursday after Bloomberg reported that Aabar was in talks to buy part of the 28.85 percent stake owned by Arabtec's former Chief Executive Hasan Ismaik, who abruptly resigned last month.