Shares in Boart Longyear have fallen more than eight per cent after the drilling company slumped to a full year net loss of $US620 million.

Boart Longyear said 2013 had been a challenging year, with falling commodities prices and increased political and economic risk for mining activity. The company predicts key commodity prices will remain weak after posting a full year net loss of $US620 million in 2013, down from $US68 million in 2012. Revenue…