Pub operator Marston's will take over the running of around 150 pubs in Wales from SA Brain, safeguarding up to 1,300 jobs in the process, the companies have revealed.
Brains' chairman said that the company had not taken the decision lightly, but recent trading restrictions in Wales due to the pandemic have put huge pressure on the business.
The 138-year-old business closed down all its pubs a few weeks ago after new rules that meant they would have to close at 6pm, and are not allowed to sell alcohol.
John Rhys, Chairman said: "This agreement marks the formation of a lasting strategic relationship with Marston's which secures the future of Brains' pubs and 1,300 of our employees within them.
"We know and trust Marston's to be excellent custodians of our pubs and, whilst this is not a decision we have taken lightly, we are confident that both our pubs - and our pubs teams - will thrive under their stewardship."
The deal means that Marston's will take over operations at Brains' portfolio of 156 pubs in Wales. They will continue to be run under the Brains brand, and will still sell the Welsh brewer's beer.
The deal, which is expected to close in February, will add to Marston's 1,368 pubs around the UK.
Ralph Findlay, Marston's Chief Executive said: "This transaction is entirely consistent with Marston's long-term strategy as a focused pub operator and strengthens our representation in South and West Wales, whilst protecting the heritage and independence of an iconic Welsh business.
"These high quality pubs are a great fit with our existing estate and will benefit from Marston's scale and operational expertise to further unlock their excellent long-term potential.
"We look forward to the pub teams joining us and to welcoming guests and the communities which they serve, back into these pubs as the country emerges from the pandemic over the weeks and months ahead."