Shaw Group Inc. said on Tuesday that problems with a subcontractor on an energy and chemicals project and troubles on another project triggered a $70 million loss in its fiscal third quarter.

Shares of the engineering and construction company dropped 12.6 percent in after-hours trading.

After markets closed, Shaw reported a loss of $70 million, or 89 cents per share, for the three months ended May 31. That compared with net income of $68.2 million, or 79 cents per share on more shares outstanding, in the same quarter a year ago.

Analysts surveyed by FactSet had forecast a profit of 68 cents, on average, in the latest quarter. Analysts' estimates typically exclude one-time items.

Revenue dropped nearly 17 percent to $1.49 billion from $1.79 billion in last year's fiscal third quarter.

Shaw said that unspecified "subcontractor execution issues" resulted in cost increases to the company on an energy and chemicals project. That reduced earnings by $112.8 million on a pretax basis, and $68.9 million after taxes.

The Baton Rouge-based company also recorded a pretax accounting impairment of $48.1 million, or $29.4 million after taxes, on loans made to Nuclear Innovation North America's South Texas Project.