Toshiba Corp.—the parent of Westinghouse Electric Co.—said it might book huge losses as a result of Westinghouse’s acquisition of the nuclear construction and integrated services business CB&I Stone & Webster Inc. (S&W).

Westinghouse closed on its agreement with CB&I in December 2015. When the deal was made, Toshiba estimated that the amount of “goodwill” resulting from the acquisition would be about $87 million. (Goodwill is a term used to identify intangible assets for which a premium is paid as part of a transaction. It includes such things as a company’s positive brand name, dependable customer base, favorable customer and employee relations, and proprietary technology, among other things.) At the time, the amount was noted to be preliminary and subject to change; the company said it would finalize the total by the end of 2016.

In the meantime, Westinghouse has been involved in purchase accounting and has studied S&W’s actual status, based on details provided after the transaction. As a result, the company found that the cost to complete U.S. AP1000 projects would far surpass original estimates, meaning that S&W’s asset values are much less than originally believed.

In July, CB&I filed a lawsuit against Westinghouse in the Delaware Court of Chancery. The dispute was related to post-closing true-up working capital adjustments. CB&I said it was entitled to $428 million, while Westinghouse used a disputed provision in the agreement to claim CB&I owed it $2 billion. On December 5, the court ruled that the dispute is for an independent auditor to decide.

However, Toshiba announced on December 27 that the goodwill booking could amount to several billion dollars. According to a story in The Wall Street Journal, the write-down could leave Toshiba with a negative net worth. That might pose a problem, because stock-exchange rules call for companies to be delisted if they report negative net worth at the end of their fiscal year and fail to repair the situation within a year.

The investment community greeted the news very unfavorably. Toshiba’s stock price plummeted in Tokyo, dropping ¥80 on Wednesday—the maximum allowed in a single day under stock exchange rules. The stock has lost about 30% of its value since the announcement was made.

Aaron Larson, associate editor (@AaronL_Power, @POWERmagazine)