The chief investment officer of AustralianSuper has warned investors the bumper returns of the past decade are unlikely to be sustained, with the $250 billion giant trimming its positions in equity markets as it braces for interest rates to move higher.

Mark Delaney has played down fears that the country’s biggest super funds will continue to take ASX-listed companies private after AusSuper’s involvement in this year’s $24 billion takeover of Sydney Airport, instead talking up plans to double the size of its London office as part of a push into offshore private capital markets.