Shares in electronics conglomerate Toshiba were untraded amid a glut of sell orders on Tuesday, as a fresh explosion rocked a quake-hit nuclear plant in Fukushima, north of Tokyo.
Toshiba, the maker of several of the reactors at the stricken power plant, had been touting its ambitions as an exporter of nuclear power technology.
Bids indicated a fall of nearly 20 percent to 331 yen, following a drop of more than 16 percent the day before, while shares in rival nuclear power makers Hitachi Ltd and Mitsubishi Heavy were also down more than 8 percent.
As radiation levels rose and Prime Minister Naoto Kan urged people living within 30 km of the plant to stay indoors, activists and politicians around the world are expressing doubt about expanding nuclear power programs.
But several analysts are retaining buy or outperform recommendations on Japanese giant Toshiba, saying panic sales sparked by the effects of the disastrous quake and tsunami, though understandable, have gone too far.
The stock move has wiped out the assumed value of the nuclear business completely, said Damian Thong, analyst at Macquarie Capital Securities in Tokyo, adding that the share price would likely bottom out once the crisis came under control.
The value of the nuclear business may fall, but it isn't going to zero, he said.
Bank of America Merrill Lynch said in a research note that nuclear power had been expected to make up 10 percent of Toshiba's operating profit in the year to March 2012, compared with 40 percent for NAND flash memory chips, the remainder made up by social infrastructure and digital products.
Public support for nuclear power may also be affected in Japan, but analysts point out that resource-poor Japan, which imports 80 percent of its energy requirements, has few options to meet its needs.
(Reporting by Isabel Reynolds; Editing by Joseph Radford)