U.S. biotechnology group Amgen has agreed to buy unlisted Decode Genetics, a pioneer in gene research, for $415 million to boost its drive to develop better targeted drugs.

Founded in 1996, Decode blazed a trail in personal genomics by trawling Iceland's unique genetic heritage, which has changed little since the Vikings arrived more than 1,000 years ago, to work out the links between genes and common diseases.

But it failed to live up to early expectations after going public in 2000 and filed for bankruptcy protection in 2009, weighed down by debts after 13 years of failing to make a profit, before re-emerging as a privately owned company.

Amgen and Decode said on Monday that the transaction did not require regulatory approval and was expected to close before the end of 2012.