Shares in engineering and contracting firm Transfield Services are almost 10 per cent weaker despite an 80 per cent rise in half year profit.

The operator of detention centres at Nauru and on Manus Island, as well as maintenance and construction services in the resources, defence and infrastructure sectors, said its diversity helped to overcome a sharp drop in earnings from its mining sector operations. Transfield made a net profit of $8.4 million in…