Dubai's main bourse amended ownership data for Dubai construction firm Arabtec on Sunday after initial figures displayed on its website fuelled a 10 percent plunge in the stock, one of the most market's most heavily traded.

Roughly an hour before the close, data on the Dubai Financial Market site indicated that the stake which Abu Dhabi state fund Aabar Investments holds in Arabtec had dropped to 14.32 percent from 18.85 percent.

Shares in Arabtec plunged to close their daily limit of 10 percent lower, helping to drag the main market index down 4.7 percent. About a third of the stock's losses occurred after the ownership figure was posted, price records showed.

After the market closed, the bourse released a statement saying the correct number was 18.94 percent - meaning Aabar had actually raised its stake in Arabtec slightly, not cut it.

"DFM also clarifies that a temporary system glitch during the last hour of (the) trading session caused the misinformation pertaining to the 14.32 percent quoted in some media reports today," the bourse said.

The level of Aabar's stake in Arabtec is important because the deep-pocketed fund has backed the construction firm's expansion to become one of the region's largest builders, helping to steer huge contracts its way.

In February, for example, Arabtec said it had signed a $6.1 billion memorandum of understanding to build 37 mixed-use, residential and hotel towers for Aabar in Abu Dhabi and Dubai.

Between June 8 and 11, Aabar cut its stake to 18.85 percent from 21.57 percent; its selling fuelled a 30 percent plunge in Arabtec's stock price as investors worried that the fund's commitment to the firm might be waning. Aabar has declined to comment on its strategy.

Adding to the mystery is the recent buying of Arabtec shares by the company's chief executive Hasan Ismaik. In late May, Arabtec said Ismaik had raised his stake to 21.46 percent from 8.03 percent; on Sunday, bourse data showed his stake had risen further to 28.85 percent.

Neither the company nor Ismaik have commented publicly on the increase, which at current market prices would be worth about $1.1 billion.

In early June, Forbes magazine said Ismaik, 37, had become the first Jordanian billionaire - and the third-youngest billionaire in the Middle East - because of his Arabtec stake, estimating his net worth at $1.4 billion. Forbes said it was not clear where Ismaik raised the money to boost his Arabtec stake.

In a separate statement on Sunday, Arabtec said its board would meet on June 18 to discuss the company's projects, among other issues.

Four of Arabtec's nine board members are associated with Aabar and Aabar's parent firm International Petroleum Investment Co, including Arabtec chairman Khadem Abdulla Al-Qubaisi. The board meeting will take place at IPIC headquarters in Abu Dhabi. - Reuters