The country’s biggest superannuation fund, AustralianSuper, has written down some of its office towers by as much as 10 per cent as the industry turns to equities to offset plummeting commercial property valuations in the financial year results.

The megafund, which tipped over $300 billion funds under management for the first time this month, returned 8.22 per cent in its default MySuper option for the year, thanks largely to a rally in tech stocks.