Bam Nuttall has posted a £20m loss for the year to 31 December 2014, blaming one “extremely challenging” contract.
The firm would not name the project but said the contract “resulted in a significant loss” for the company.
According to a statement by the firm’s board, the contract is now “under control” and will be completed during 2015.
Overall, the firm posted a trading loss of £20m compared with a pre-tax profit of £10.7m reported in the year to 31 December 2013, amounting to an operating profit margin of -3.3 per cent.
Bam Nuttall saw turnover rise to £774m, up from £756m the previous year.
The firm said it had grown its order book outside London and the South-east, while it has also won a place on the £416m 6 km western section of the Thames Tideway Tunnel in a joint venture with Morgan Sindall and Balfour Beatty (BMB).
It is also looking to bid for work on High Speed 2 in a joint venture with Morgan Sindall and Ferrovial.
Earlier in the year, the firm was involved in a dispute with Cambridgeshire County Council over alleged defects to its guided busway, which could total around £50m.
Bam Nuttall is the third major contractor to report significant losses over the past week.
Yesterday, ISG posted a loss of £27.8m on the back of several problem contracts, while Laing O’Rourke’s European business recorded a loss of £53m, blaming “cost inflation and delays” on three UK contracts won during the recession for the financial hit.