Motor parts manufacturer Bosch is closing its south Wales plant with the loss of 900 jobs.
The company will transfer work to Hungary in 2011.
Management of the German-owned company spent Thursday informing the workforce, following three months of consultation.
Plans being considered at the site in Miskin, near Cardiff, had included the option of 300 job cuts or complete closure.
In a statement, it said consultations are now being extended until February, as unions and staff attempt to thrash out redundancy terms.
The firm said it was facing the worst economic downturn for decades, saying it had “left its mark on the Bosch Group”.
It said compared to 2008, sales of its alternator products made at the site in Miskin were down 45% in 2009.