Old Mutual and Pareto announced the R10 billion deal in a joint statement.

The transaction was subject to Competition Authority approval and other conditions associated with a transaction of this nature.

The asset swap would mean Pareto would acquire the 50 percent share of Menlyn shopping centre it did not already own from Old Mutual. Old Mutual would acquire the 50 percent share of Cavendish it did not own from Pareto, with the net consideration payable in cash.

Managing Director of Old Mutual Property, Peter Levett, said the asset swap was beneficial for both companies.

He said the decision was based on ensuring optimal growth in their respective property portfolios.

"We are very pleased with this value enhancing, which gives us outright ownership of a key retail centre, Cavendish, and enables us to access additional development opportunities within our portfolio," he said in a statement.

For the past five years, Old Mutual and Pareto have equally owned the two malls.

Menlyn was undergoing a development upgrade and together these assets represent around R10 billion of prime retail property investment.

Pareto CEO Marius Muller said they were thrilled with the transaction.

"Menlyn Park shopping centre is an unrivalled retail property that is an ideal fit for Pareto's portfolio, especially as its current R2 billion redevelopment project reflects Pareto's strategy of adding value to our assets," he said in a statement.