Shares in BAE Systems dropped after the defence group failed to secure a follow-on contract for the production of vehicles for the US Department of Defense (DoD).The full implications of this decision cannot be assessed until consultations with the DoD have been completed regarding their intentions to transition the programme to the new arrangements, the group said.The current contract, which will see production of the vehicles through to the fourth quarter of 2010, was expected to generate $2bn in both 2009 and 2010.