Companies involved in track maintenance for London Underground saw their shares fall yesterday after two derailments over the weekend, apparently caused by track faults.
Jarvis, which is still awaiting judgement on the Potters Bar rail crash last year, owns one third of Tube Lines, the maintenance company for three LU routes including the Northern Line.
Balfour Beatty and WS Atkins are among the five partners in Metronet, which has responsibility for the other nine lines.
Jarvis shares lost 11p to 290p after it emerged Tube Lines engineers had carried out maintenance work on the track at Camden Town station in north London on the Northern Line only hours before a train hit the tunnel wall.
Balfour Beatty and Atkins share responsibility through Metronet for the Piccadilly Line, which had a derailment between Hammersmith and Barons Court stations in west London on Friday evening. Balfour shares lost 10p to 467.5p yesterday and Atkins' 5.5p to 213.5p.
Although crashes are rare on London Underground there are fears that the part-privatisation of the system might lead to a lowering of safety checks to cut costs. Bob Crow, general secretary of the rail union RMT, threatened this weekend to hold a strike ballot unless the public-private partnership was dismantled.
The drivers' union Aslef expressed concerns over maintenance and said several drivers had reported a bumpy ride on the approach to Camden Town station.