Japanese electronics and energy giant Toshiba has said its chairman is resigning to take responsibility for problems that will result in a 713 billion yen (€5.9 billion) loss in its nuclear business.
Toshiba warned that all the estimates it announced on Tuesday may change "by a wide margin" because of uncertainties.
Earlier, the company delayed reporting its official financial results by a month, citing problems with auditing related to the losses in its nuclear business. That sent Toshiba shares tumbling 8% in Tokyo trading.
The company said chairman Shigenori Shiga will step down from the board but will remain as a Toshiba executive. He is quitting over the big losses related to the acquisition of CB&I Stone & Webster by its US nuclear unit, Westinghouse.
Toshiba said its net worth was in the negative, at minus 191 billion yen (€1.6 billion) at the end of last year, but it said it hopes to take measures to fix that by the end of March.
Auditors questioned the company's reporting on the acquisition of CB&I Stone & Webster. Toshiba denies any wrongdoing.
However, the company was already grappling with a scandal over company officials' doctoring of accounting books to meet unrealistic profit targets.
Toshiba is expected to restructure its ailing nuclear business, but nothing has been announced. Japan's nuclear sector was thrown into crisis after multiple meltdowns of reactors at a power plant in Fukushima prefecture triggered by the March 2011 earthquake and tsunami.
In its preliminary results, Toshiba said it anticipates a group net loss of 500 billion yen (€4.2 billion) for April-December, including the 712.5 billion yen hit from its US nuclear business.
The company is forecasting a group net loss of 390 billion yen (€3.2 billion) for the full year to March 31, instead of the 145 billion yen (€1.2 billion) profit it had anticipated earlier.