* Losses mainly due to derivative investments
* Shares fall almost 6 percent in Abu Dhabi
ABU DHABI, Sept 1 (Reuters) - Abu Dhabi investment firm Aabar, which holds a stake in Daimler, made a net second-quarter loss of 2.18 billion dirhams ($594 million) on investment losses in derivative instruments.
"But this has been compensated by the fair value gain of the shares which we reported under comprehensive income which had a net increase for Aabar shareholders totalling 1.73 billion dirhams," Mohamed al-Husseiny, Aabar Chief Executive told Reuters by phone on Tuesday without elaborating.
Aabar made a loss of 228.95 million dirhams in the second quarter of 2008.
Shares of Abaar were down 5.67 percent at 0757 GMT on the Abu Dhabi stock exchange.
Aabar is an investment company controlled by the International Petroleum Investment Company (IPIC), which is wholly owned by the government of Abu Dhabi.
IPIC is one of the investment vehicles used by the Abu Dhabi government to invest oil income. Abu Dhabi pumps most of the oil produced by the UAE, the world's third-largest oil exporter.
Fuelled by a six-year oil boom, Abu Dhabi has invested billions of dollars in developing its infrastructure and propelling itself on the global stage.
Aabar has been on the expansion trail since IPIC took control of the firm in 2008.
In July, Aabar said it planned to buy a 32 percent stake in Virgin Group's space travel unit Virgin Galactic, in Abu Dhabi's latest effort to lure tourists and diversify away from oil.
Shareholder equity increased to 10.93 billion dirhams in the second quarter from 9.2 billion dirhams in the first quarter.
"Forecasting earnings is difficult because income is dependent on investments we have," Husseiny said. "But some of our investments like Daimler are performing well and we can derive benefits," he said.
Aabar's total assets grew to 27.87 billion dirhams ending June 2009 versus 3.38 billion dirhams at the end of December 2008. ($1=3.673 Uae Dirham) (Reporting by Stanley Carvalho; Editing by John Irish and Jon Loades-Carter)