Writedown fears maul Toshiba rally

Conglomerate claims sufficient funding on hand, but nuclear business risks signal trouble

Toshiba Corp's impending multibillion-dollar writedown has triggered one of the worst-ever share declines for a major Japanese company, with ratings downgrades and investor pessimism erasing almost all of its 87 percent rally this year.

Shares in the electronics and industrial conglomerate fell 17 percent to 259 yen at the close on the Tokyo Stock Exchange on Thursday. Toshiba said it may write down billions of dollars of an acquisition made by US unit Westinghouse Electric, fueling a share decline this week that has wiped out about 800 billion yen ($6.8 billion) in market value.