The state-owned fund, which owns stakes in high-profile names such as German carmaker Daimler (DAIGn.DE), commodities trader Glencore (GLEN.L) and Italy's UniCredit (CRDI.MI), had been buying up shares in recent weeks through subsidiaries and raised its stake to 10.45 percent last month.

An official at the Dubai Financial Market said trade done on May 6, and settled on May 8, had lifted Aabar's position to 53 percent. The new shareholder structure will be updated on the bourse's website on Monday.

Officials from Aabar and Arabtec could not be reached for comment.

In April, Arabtec appointed four Aabar executives to its board, including a new chairman in Khadem al-Qubaisi who holds the same post at Aabar.

Arabic daily Alrroya quoted Qubaisi as saying the sovereign fund had taken the controlling stake in an interview on Saturday.

"The company (Aabar) has bought a 23-percent stake directly from Arabtec during the last period, while it acquired the remaining 30 percent from other shareholders," Qubaisi was quoted as saying.

Qubaisi said the investment was "a successful opportunity," adding Aabar is planning to award more real estate contracts to Arabtec in Abu Dhabi. In April, it gave the builder a $60 million contract to build a residential development in the oil-rich emirate.

Last week, the Abu Dhabi government identified an Arabtec consortium that includes Greek and Turkish firms as the preferred bidders for an estimated $3 billion contract to expand its international airport.

Aabar tried to acquire a 70-percent stake in Arabtec, the United Arab Emirates' largest builder by market value, in 2010 in a $1.7 billion deal that was eventually dropped.

Arabtec shares were down 2.37 percent at 0749 GMT. The stock is up 94 percent year-to-date.

(Reporting by Praveen Menon; Editing by Amran Abocar)

• A Permanent Economic Emergency