This chart series is based on wholesale trader prices in US$ per tonne, as reported, for butter, skim milk powder, whole milk powder, and cheddar cheese. These prices are converted into NZ$ at the rate applicable when the US$ prices are reported.
However, most trade transactions are on a contract basis, and the price reports used for this series will only rarely pick up such contract pricing. Nor do these prices reflect currency hedging a producer like Fonterra may do.
Also note, that prices quoted are "Oceania" prices, not specifically New Zealand prices.
The globaldairytrade internet selling platform prices are only a component of the prices used for these charts - those prices cover the specific products in their twice-monthly auctions.