Sweden's four pension buffer funds, with Skr895.8bn (€95.4bn) of assets under management used to accumulate savings for the national pension system, have generated an average return of 6.58% in the first half of the year.

The funds, called AP1 to AP4, had relatively similar returns ranging from 6.2% to 7% for the period. However, the similarity in their returns has reignited concern the funds' portfolios are too similar, despite being established as competing vehicles.