The New Zealand Superannuation Fund has made investment gains of 33% since March.
Unaudited figures show the fund has made a return of about $3.6 billion since the low point of global equity markets in early March.
It made gains of $845 million, or 6%, in July and $421 million, or 3%, in August.
The fund had made a large loss during the height of the recession.
Earlier this year, the Government blocked payments because it said it did not make sense to borrow money to invest in shares, which dominate the fund's portfolio.
But financial commentator, Bernard Hickey, says subsequent events have shown the fund could have used the money to buy shares cheaply, and emerge stronger when the rebound occurred.
However Mr Hickey qualifies this by saying the 5.3% return on investments since the fund was started is not brilliant, though it exceeds returns by some private sector managers.
The New Zealand Superannuation Fund was set up to part-fund the Government's future pension bill and is worth about $15 billion.