Like other banks that have reported results this week, the former Royal Bank of Scotland said the bad debts have arisen from the impact of coronavirus on the UK economy.
"What the final bill is will depend on 'the effectiveness of government support schemes in delaying and reducing the level of economic distress experienced by our personal and commercial customers,' the FTSE 100-listed lender said in its results statement.
“We believe the full year 2020 impairment charge is likely to be in the range of £3.5-4.5 billion," it added.
Without the bad debt charge, Natwest posted an operating profit of £2.1bn for the six months to June 2020.
A strong performance from investment banking helped the interim numbers. NatWest Markets' income increased by 44.4% ignoring one-offs and in contrast to the retail and commercial arms, which declined by 9%.
Alison Rose, NatWest's chief executive said the bank had a robust capital position, ‘underpinned by a resilient, capital generative and well-diversified business’.
"Through our strong balance sheet and prudent approach to risk, we are well placed not only to withstand Covid-19 related impacts but also to provide the right support to those who will need it most in the tough times to come,” she added.
The bank said that having been asked to suspend dividend payments by its regulator, it would continue to review the situation and will look to resume distributions to ordinary shareholders in due course.
Lots of questions but few answers say analysts
Nicholas Hyett, an equity analyst at Hargreaves Lansdown said: "The longer-term challenge faced by all UK banks is how to make money when super low-interest rates increasingly look like they’re here to stay.
"Even before impairment charges NatWest’s operating profits were down 60%. We’re not sure NatWest has an answer to that, especially since it’s shrinking investment bank means interest income is getting ever more important for the business.
"NatWest is by far the best capitalised big bank in the UK, but with clear growth options few and far between and dividends or buybacks off the table for now, we’re not sure the group’s able to make the best use of its position of strength.”
David Madden at CMC markets pointed out that in the six month period Natwest's operating expenses were £814mln, up over 100% from last year.
The surge in expenses was down to an increase in litigation, strategic and conduct costs even before the loan impairments, he said, though on the bright side, risk-weighted assets (RWAs) dropped by 6.8% to £32.8bn.
"Bad debts are tipped to rise in the quarters ahead, but at least NatWest Group is very strong from a liquidity standpoint."
Shares rose 1.6% to 107.6p.
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