Intu's Uxbridge shopping mall could be sold in a £3.4 billion deal which would create the country's largest property company.
The deal is understood to bring together Intu's Lakeside, Trafford and Uxbridge centres and Hammerson's Bicester Village, Brent Cross and Birmingham's Bull Ring.
The value of the joint property portfolio is estimated at £21 billion, which would make it the largest property company in the country.
In 2014, Malaysian pension fund Kumpulan Wang Persaraan purchased an 80% stake in the shopping centre from Intu, which retained 20% and continued to manage it.
getwestlondon understands Hammerson is keen to maintain the large portfolio, including Intu Uxbridge as well as retail and leisure destinations across the world.
Hammerson shareholders would control 55% of the joint company while Intu's investors would own the remaining 45%.
Hammerson shares fell by 3% when the news broke, while Intu shares surged 18% as investors backed the supermall consolidation.
John Strachan, chairman of Intu, said: "A combination of both Intu and Hammerson will create a more resilient, diversified and stronger group that we believe will benefit all our stakeholders.
"Intu offers high-quality retail and leisure destinations in the UK and Spain, which when merged with Hammerson's own top-quality assets in the UK, in France and in Ireland, present a highly attractive proposition for retailers and shoppers in Europe's leading cities."
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