Royal Bank of Scotland swung to a third-quarter loss today, hit by costs related to past misconduct and restructuring.
The figures have cast fresh doubts on when the government might begin to recoup more of its 2008 emergency investment.
The Edinburgh-based bank, which also owns Ulster Bank, today reported a loss of £469m, compared with a profit of £952m the same time last year.
That was more than twice the £231m loss estimated by analysts, according to a poll supplied by the bank.
RBS also said it would miss an end of 2017 deadline to sell its Williams & Glyn branch network, a condition of its 2008 state rescue.
Today's results from RBS show that Ulster Bank's operating profit fell from £108m to £68m over the third quarter of this year.
Ulster Bank had said it was able to release €75m in provisions originally made to allow for expected bad debts in the third quarter of 2015, but the write backs this year were substantially lower.
RBS chief executive Ross McEwan is in the midst of a vast, multi-year restructuring of the bank, which includes asset sales, job cuts and multi-billion dollar charges to settle litigation and pay fines for historic regulatory breaches.
The bank's losses were partly driven by a fresh £425m misconduct charge and a rise in third quarter impaired loans to £144m.
The bank also reported £469m of additional restructuring costs, largely as a result of its extended struggle to sell Williams & Glyn.
But unlike rivals Lloyds Banking Group and Barclays, RBS did not record any provisions for repaying customers mis-sold payment protection insurance after taking a £450m charge in the last quarter.
The bank reported higher than expected adjusted income of £3.494 billion for the three months to the end of September, reflecting efforts to step up lending to maintain its status as Britain's biggest corporate lender.
RBS, which succumbed to a £45.5 billion state bailout during the 2007-09 financial crisis, has not made an annual profit since 2007.
The UK government is currently sitting on a £25 billion-plus loss on its investment