The Superfund has today published its annual results, and the fund has grown by $3.7 billion in the last year alone.

The fund's size is now $43.1 billion.

Superfund CEO Matt Whineray told Heather du Plessis-Allan that they are happy with the results. 

"It was a positive year and another year of value add from the team." 

The news comes as the Superfund finds itself in controversy for its role in the Auckland light rail.

A proposal from the group was added to the mix early last year but the Prime Minister says it's still being considered.

National leader Simon Bridges called the move 'deeply cynical', but it has the backing of the Government.

Whineray says that they are always open to investment opportunities. 

"If we can find one where we get an intersection between our commercially driven investment approach and something that makes a difference for Auckland, and this certainly will, then we are happy to take a look at it." 

He says that they are expecting to make a return on their investment.