Investor interest was strong Wednesday as Abu Dhabi's state energy company listed a stake in its retail distribution arm, the first time the emirate has sold shares in one of its oil firms.

The Abu Dhabi National Oil Company said it had raised $845 million by floating 10 percent of its subsidiary ADNOC Distribution, a landmark share offering as Gulf energy firms open up to outside investments.

The initial public offering price for the shares was at 2.5 dirhams (68 US cents) and by 0915 GMT they were trading at 73 cents.

ADNOC said the IPO brought the subsidiary's market capitalisation to $8.5 billion, making it the fourth-largest firm on the Abu Dhabi Securities Exchange.