Sky News has reported that Hutton Collins, which acquired the group for £100m in 2013, has sold a majority stake to private equity firm Three Hills Capital Partners (THCP).
FPP Asset Management will also become a new investor in the business.
Byron declined to comment when contacted by BigHospitality, but sources told Sky that the deal was likely to involve a company voluntary agreement, which could see a chunk of the group’s estate close next year.
The 'better burger' brand, which launched a strategic review in October, is understood to be valued at just £15-£25m.
Byron has doubled its number of sites to over 70 since 2013, but has been unable to escape the headwind of cost pressures and increased competition from delivery and high street rivals facing the restaurant industry.
The group placed four sites on the market earlier this year, and information distributed to potential bidders indicates that 13 of its sites are loss-making, with a further dozen marked for review.
Sky understands that the rescue package will see millions of pounds injected in to Byron to fund future plans.
The news follows a rocky year for UK burger brands. Meatcure has gone in to liquidation after shutting four of its five sites, while Handmade Burger Co was bought out of administration in July with the closure of nine of its restaurants.
Byron founder Tom Byng, who opened its first restaurant in Kensington High Street in 2007, announced he was stepping down as CEO late last year.