The UK's largest power firm, British Energy, has suffered losses of £87m in its first quarterly results since it relisted on the London Stock Exchange.
The company expects to meet its output targets for the year
Forward-selling of contracts meant the nuclear power generator did not see the full benefit of a rise in electricity prices in the three months to December.
The pre-tax figures, which compare to a loss of £10m a year earlier, were also hit by decommissioning costs.
A slump in wholesale prices pushed the firm towards insolvency in 2002.
British Energy's shares - which were relisted last month - fell 2.4% to 248.75p on news of the increased loss.
The company negotiated a rescue deal with the government and major creditors, finally completed last year.
This gave creditors new bonds and 97.5% of the firm's shares in exchange for cancelling £1bn of its debt.
Last month the firm suffered a shutdown at its Heysham plant in Lancashire, but said it expects the affected unit to return to service in March.
Chief executive Mike Alexander said the company was set to meet its full-year output targets, which were revised in November after a series of other outages.
"Output is not great, but at least they've reiterated their full-year target," said analyst Jason Steed, at Lehman Brothers.