German real estate Spezialfonds achieved their best annual performance since 2009, according to the MSCI SFIX index, returning 3.4%.

But analysis by MSCI shows that the gap between the best and worst performing funds is widening.

Of the 170 or so funds covered by the index – amounting to a market coverage of 65% – the best performing funds are performing better and the worst performing funds are in decline.

The year in which a fund was launched – or vintage – was found to be the principal factor in determining performance, according to the study by Sebastian Gläsner, vice president at MSCI.

Gläsner found that a fund’s vintage was more important than, for example, its sector weighting.

The results were announced at a press conference in Frankfurt, during which Gläsner said only 35% of funds with a negative return in one year managed a turnaround in the following year. “Once a fund is off the path it is difficult for it to comeback,” he said.

The remaining 65% of funds continue to post a negative returns “very often also into the following years”.

Samples of younger funds have a much narrow return spread than the overall MSCI sample, it was revealed.

Investors and managers discussed the “vintage effect”. Ingo Bofinger, head of real estate at Gothaer Asset Management, said: “We have been indirectly invested in real estate since 2004, and especially funds which have first invested between 2004 and 2006 are struggling today.”

Eitel Coridaß, managing director at Warburg-HIH, said the most successful funds were mainly those that invested during the global financial crisis.

“It is important to have courage and trust in the manager to go into markets when they are down after correction phases,” said Coridaß.

Bofinger said it was important to “continuously invest”. The insurer invests with lower or no leverage during time of high prices.

Total assets in real estate Spezialfonds increased in 2015, up by €8.2bn to just under €70bn.