Diamond Offshore on Monday reported a net loss for the second quarter amounting to $589,937, compared to a profit of $87,425 in the corresponding period of 2015.

The company’s revenues dropped by 17% during the quarter to $388,747, compared to $470,54 in the prior-year quarter.

The drilling contractor explained on Monday that its results for the second quarter were significantly impacted by impairment charges and related taxes of $612 million, primarily relating to the carrying value of eight semi-submersible rigs and associated inventory.

Operational efficiency of the company’s fleet was 92.7% in the second quarter, compared to 98.2% in the first quarter of 2016, and compared to 95.9% in the second quarter of 2015.

The decline in operational efficiency was primarily driven by issues experienced within the ultra-deepwater floater category related to four unplanned retrievals of blowout preventers, the company said.

As of June 30, 2016, the company’s total contracted backlog was $4.4 billion, which represents 28 rig years of work.

Reflecting on the market, President and Chief Executive Officer Marc Edwards, said: “Although the market continues to be challenged, our focus is on striking a balance between controlling costs and laying the foundation to ensure Diamond Offshore is well positioned for the recovery.”