Currency specialists say the sale of a large amount of currency by the Reserve Bank is unlikely to have been to try to bring down the high-flying New Zealand dollar.
They say it could herald a new Reserve Bank policy which will see it actively manage its foreign currency reserves to make money for the taxpayer.
The bank sold $NZ200 million in December, its biggest currency intervention in two years and the biggest sale of the Kiwi by the bank since 2008.
Westpac currency strategist Imre Speizer said the sale was too small to have made any dent in the currency's recent rise.
But the central bank could be following the Reserve Bank of Australia which has a longstanding policy of managing its currency reserves to make a return for the taxpayer.
"December was a month where the Kiwi dollar against the US made a recent high of 84.77, so if they indeed sold around that area they would have done opportunistically and successfully and made money out of it."
Strategist at Edge Capital Partners, Graham Parlane, says the Australian central bank has a good record although it did make large losses during the Asian crisis in the late 1990s which it recouped later.
He said the New Zealand dollar looks overvalued and now is a good a time to be selling the currency.
The Reserve Bank is not commenting on Thursday.