LONDON (Bloomberg) - Alea Group Holdings Ltd., a Bermuda-based reinsurer providing property and casualty insurance services, said net asset values fell 12 percent in the first half due to impairment costs.

Net asset values on June 30 were $296 million, or $1.7 per share, compared to $336.7 million, or $1.94 on December 31, the company said in a Regulatory News Service statement yesterday. Net loss after tax for the six months ended June 30 stood at $50.1 million from $44.7 million a year earlier.

"The primary driver of the loss for the period is the recognition of an impairment on our financial assets of $50.6 million," CEO Jeffrey Rosenthal said in the statement.

The company described the net loss as "disappointing".

Alea said it does not plan to pay an interim dividend.

Mr. Rosenthal was named president and CEO on 1 April 2010, replacing Mark Cloutier.