The IT services company estimated the value of the extensions to be about $1.6 billion.
General Dynamics first outsourced its IT needs to CSC in 1991 as part of a 10-year, $3 billion contract between the companies. Among the services CSC has provided the defense contractor are desktop support, network management and help with the operations of General Dynamics' data center.
After the announcement of the deal, shares of CSC closed regular trading up 16 cents, or 0.3%, to $56.15. At the bell, shares of General Dynamics were off 36 cents, or 0.3%, to $106.64.