TEPCO posted a record $15 billion loss for the financial year ended March and its under-fire president resigned to take responsibility for the worst nuclear crisis since the Chernobyl disaster 25 years ago.
Shares in the utility closed at 334 yen, down nearly 85 per cent since the day before the March 11 earthquake and tsunami crippled cooling systems at the Fukushima Daiichi nuclear plant, triggering reactor meltdowns.
The firm posted an annual net loss of 1.247 trillion yen ($15 billion), the biggest ever for a non-financial Japanese firm. The company did not give an earnings forecast for the current financial year.
It warned the "significant deterioration" in its financial position "raises serious uncertainty" about its ability to continue as a going concern.
It faces huge costs from damage to facilities as well as in procuring replacement fossil fuels on top of compensation claims that some analysts estimate to be as high as 10 trillion yen.
"The company said it has priced in as many costs as possible, but unfortunately, investors do not believe those words so uncertainty remains strong and shares are likely to continue being volatile," a senior portfolio manager at a Japanese asset management firm told Dow Jones Newswires.
The loss for Japan's biggest utility comes amid heavy criticism over its handling of the emergency. The prospect of massive compensation claims prompted the government to devise a rescue plan using public and industry funds, with no ceiling set on payments.
"For TEPCO to pay compensation and to continue operating freely as a corporation, a limit to its damage payments would need to be established," said Nomura Securities analyst Shigeki Matsumoto.