Johnston Press, publisher of the i, The Scotsman and the Yorkshire Post, has detailed a rescue plan aimed at ensuring its survival.
The newspaper group put itself up for sale last month, but said none of the offers it received were strong enough.
It now plans to file for administration and says the firm’s assets will then immediately be bought by its lenders.
If the deal is approved by the courts, it will preserve jobs and stabilise the business, Johnston Press said.
But shares in the Edinburgh-based company are now worthless and will no longer trade on the London Stock Exchange from Monday.
And some staff will see the value of their pensions affected, the firm has warned.
Johnston Press is one of the largest local and regional newspaper organisations in the UK, but has debts of £220m which are due for repayment in June next year.
The group said in a statement: “This is the best remaining option available as it will preserve the jobs of the group’s employees and ensure that the group’s businesses will be carried on as normal.
“The group hopes that this transfer will be completed within the next 24 hours.”
But Custos Group – the largest shareholder in the newspaper group with 25% – says it will try to block its collapse into administration and has accused the company’s board of incompetence.
In a statement, Custos chief executive Christen Ager-Hanssen described the move to offload the staff pension scheme as a “disgrace and a vulgar display of the worst elements of capitalism”.
Custos, whose shares will soon be worth nothing, insisted the publisher had a reasonable cash flow and was not insolvent.
Johnston Press chief executive David King said in a letter to staff that the move had not been “an easy decision”, but it would reduce debt and secure new money for the business.
“We are very confident that this is not the end of the story, but the beginning of a new phase in which we work with the new owners of the group to give shape to a new future,” he wrote in a letter to staff.
Mr King said the debt had “constrained us” and that none of the offers they had received for the firm was enough to repay it.
He apologised to staff with a defined benefit pension scheme – some 250 current employees – warning their future payments would be affected by the rescue deal.
“The negative effects on the scheme are an inescapable consequence of taking the steps needed to ensure the future of the business,” he wrote.
Mr King said he intended to stay on as chief executive and said the rescue plan was better than “a lengthy and unpredictable administration process”.
Analysis: Administration ‘one of the better outcomes’
By Douglas Fraser, BBC Scotland business and economy editor
Plunging Johnston Press into administration may be one of the better outcomes for the papers and websites the company has controlled – many of them important to communities from Fraserburgh to Eastbourne.
Facing a debt repayment deadline next June, with no sign of a refinancing deal, and with the market valuation of the company below £3m, Johnston Press was cornered.
In the past five weeks, it has sought a buyer, but failed to find one with enough to tackle the debt.
The deal it has struck with bondholders is that they keep the titles together, take a haircut on the debt and put new funding into the papers to keep the presses rolling – while shedding the defined benefit pension scheme.
The new owners could sell it on to a company that knows more about publishing news.
Even if it doesn’t, the drop in debt means the outcome is already better than what have been truly painful years for these titles.
But in common with many other conventional news publishers, they’re struggling to find a new business model that works.
Meanwhile, the National Union of Journalists has said it has “significant concerns” about the long-term intentions of the newspapers’ new owners.
The union is demanding “a commitment that this is not a transition leading to a carve-up of the group motivated by asset-stripping rather than a commitment to journalism and publishing”.
The NUJ is expected to meet Johnston Press management on Monday.
The publisher has titles covering more than 200 locations from Scotland and Northern Ireland to the south of England.
It was founded in Falkirk in 1767, and listed on the London Stock Exchange in 1988, growing through acquisitions.
The i, which was first launched in 2012 and sells for 60p on weekdays and £1 on Saturdays, is seen as the jewel in the crown of its papers.
In its latest results, Johnston Press reported a 10% fall in revenues during the first half of 2018. It swung back to a profit of £6.2m for the six-month period, but this was mainly due to a one-off accounting gain of £8.8m.
In September, the i recorded a year-on-year circulation drop of 9% to 242,408 copies.