Boart Longyear's (BLY) credit rating has been downgraded by ratings agency Standard and Poor's.
The drilling services provider's corporate credit rating has been downgraded to CCC , from B.
Its secured note rating was downgraded to B, from BB-.
The group's senior unsecured note rating was cut to CCC , from B.
The group swung to a full-year loss when announcing results last month, posting a net loss of $US620 million in 2013, compared with a $US68 million profit in 2012.
The result was affected by $US491 million in restructuring charges and asset impairments and the group declined to offer guidance due to market uncertainty.