Atkins’ unsuccessful pursuit of Parsons Brinckerhoff cost the firm £4.5M in external fees.
In a trading update, the firm said this would be “treated as an exceptional cost in the six months ending 30 September 2014”.
Parsons Brinckerhoff was eventually sold by Balfour Beatty to WSP earlier this month, after months of speculation.
Atkins also reported “a mixed first half” in its UK and Europe business compared to the previous year, and that “financial performance continues to be impacted by a number of outstanding variation negotiations”.
It said it would have to make staff cuts in its aerospace, water, and environmental business due to “utilisation issues”.
The statement continued: “There is good ongoing demand for our services as the Government continues to implement its strategy of investment to meet the infrastructure needs of the UK economy.
“In North America we completed our restructuring activities with the introduction of a new technical professional organisation at the beginning of the year. While the implementation of this new operating model, combined with our continued focus on overhead reductions, is expected to deliver a margin improvement for the year as a whole, limited benefit is expected in the first half results.
Our Middle East business has had a strong first half as we have progressed with the mobilisation and design delivery on a number of metro projects. This is expected to contribute to a significant year on year performance improvement for the region.
“Our Asia Pacific business is trading in line with expectations as it has continued to implement its geographic and sector diversification strategy.
“We were pleased to complete the acquisition of Nuclear Safety Associates, Inc earlier this month, in another step towards our strategy to be one of the world’s leading Energy consultants. In addition, organic growth in our existing business continues to be supported by significant market opportunities.”
Atkins said its financial position remains strong, supported by continued focus on cash generation across the business.