US car parts to electronics group Delphi saw its shares fall 16% on Friday after it warned it could be facing financial difficulties.
Delphi may seek help from former parent General Motors
The firm said it was vital unions agreed to tough restructuring of its unprofitable operations.
Delphi also announced it had started to draw $1.5bn (£844m) from a $1.8bn revolving credit facility in order to stay afloat.
The company is also said to be seeking help from former parent General Motors.
Delphi was spun out from GM in 1999 and the US car giant remains its main customer.
Some analysts suggest Delphi may seek to shift some of its plants back to GM.
Fellow car parts business Visteon achieved a similar arrangement with its former owner Ford back in May.
Delphi reported a $403m net loss for the first quarter of 2005, and is struggling with high wage and benefit costs.
"Delphi certainly is turning up the pressure on the unions during a critical phase of negotiations," said analyst Mark Oline, managing director of Fitch Ratings.
Delphi releases its second quarter results on Monday.