Irish stocks have fallen by 3% in morning trading in the wake of revelations of massive fraud at another major US company.
Telecoms giant, Worldcom, faces charges of fraud of up to €4bn. The firm may be forced to let go 17,000 workers because of the scandal.
The firms auditors for 2001 and the first quarter of 2002 were Arthur Andersen, who were charged with obstructing justice in the Enron scandal.
The chief financial officer, Scott Sullivan, has been fired, and senior vice president and controller David Myers has resigned.
It's believed to be among the biggest ever cases of accounting fraud.