This trend had emerged from analysis of data covering the past four years.

Provest also said that although there was less of a correlation between the earnings of property loan stock companies and their exposure to the retail sector, the top performers were also those with the highest exposure to retail properties.

It reported that the analysis showed that the retail property element outperformed both industrial and office property components of unit trusts.

Provest said the property unit trust with consistently high exposure to the retail sector over the past four years was Sycom.

The fund also showed the highest average growth in distributions with an average 3,2% a year.

It reported that property unit trust Capital had the lowest retail exposure, at present 7%, and showed a negative 4,9% growth rate over the past four years.

The top four property loan stocks measured by year-on-year earnings growth were those with the highest exposure to retail properties, namely Atlas, Hyprop, Premium and Spearhead.

Mariette Warner, head of securitisation and fund management at Standard Bank Properties and manager of the Standard Bank Property Income Fund, said another reason for the direct correlation between the earnings growth of property unit trusts and their exposure to retail was that the retail holdings of property loan stock portfolios were not the same quality as those of property unit trusts.

"The big regional shopping centres seldom change ownership. Because of the longer history of the property unit trusts they developed their holdings as opposed to trying to buy them," Warner said.

She said an exception to this rule was property loan stock company Growthpoint, which had a "merger/ acquisition" history. "They merged and acquired regionals built some time ago and subsequently expanded and then refurbished."

She said other property loan stocks driven by good retail were Hyprop, Atlas and Spearhead.