GDT dairy auction: how global milk prices move the Kiwi

The GDT dairy auction is the Global Dairy Trade event, held twice a month, where dairy companies sell milk powder, butter, cheese and other products to buyers around the world, and its result works as a reference price for global dairy. Dairy is a large part of New Zealand's exports, so the GDT Price Index is read as a pointer to the country's export income and to the Kiwi.

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By Mike. Explanation updated 2 Oct 2026; the dates and moves below update with the research.

GDT dairy auction in short

Next release: Not on our calendar yet. It appears once the date is confirmed.
Published by: Global Dairy Trade
When: Twice a month, on the first and third Tuesday, starting at 12:00 UTC. That is 14:00 in Amsterdam in the European summer and 13:00 in the winter. An event runs for about two to three hours and the results follow shortly after it closes. In New Zealand it is already the early hours of Wednesday.
Currency: New Zealand dollar (NZD)
Impact: Medium: it moves the currency when it surprises
The line read first: The change in the GDT Price Index since the previous event
Also watched: Whole and skim milk powder, two of the products behind Fonterra's farmgate milk price
Owned by: NZX, Fonterra and the European Energy Exchange (EEX)
Prices in: US dollars per tonne

How the GDT dairy auction works

Each trading event is an ascending-price auction held online. Bidders enter the quantity they want at an announced price, and the price rises round by round until demand no longer exceeds the supply on offer.

Products include whole and skim milk powder, butter, anhydrous milk fat, cheddar and mozzarella, offered for shipment in up to six different months. Sellers include Fonterra and dairy companies from the United States and Europe.

The GDT Price Index measures the change in prices since the last event, as a weighted average of the price changes. Between the main events, GDT runs smaller Pulse auctions for a few products.

Why the GDT dairy auction moves the Kiwi

Milk powder, butter and cheese made up 30% of New Zealand's goods exports in 2025, according to Stats NZ. Higher dairy prices mean more export income for the country.

Fonterra's farmgate milk price, what it pays New Zealand farmers for their milk, is based on prices for milk powders, butter and milk fat sold on and off GDT. A run of higher auction prices lifts farm incomes and, in time, spending in the regions.

Export prices also feed the RBNZ's view of the terms of trade: the price of what New Zealand sells against the price of what it buys.

How to read a GDT result

The market forms a view before each event, partly from dairy futures traded on NZX and from the Pulse auctions in between. The change in the index against that view is what counts.

A single event usually moves the Kiwi less than a CPI release or an RBNZ decision. A large change, or several events in a row going the same way, gets more attention, and so does a move in whole milk powder.

The result lands in the European afternoon, when the Kiwi also trades on European and US news, so the reaction can be hard to separate from everything else.

What the New Zealand dollar did on the last release days

Our calendar keeps the exact time of each release since 16 September 2026. The first GDT dairy auction after that date will show here with the New Zealand dollar's move around it.

For scale: on an ordinary day the New Zealand dollar moves 0.20% against the basket from one London opening to the next, either way, on average over the 250 trading days since 14 Oct 2025.

The forecast, the figure itself and what it changed in our view of the currency are in the app, next to the research.

Questions about GDT dairy auction

What time are GDT auction results released?

Each event starts at 12:00 UTC on a Tuesday and lasts about two to three hours, and the results are published shortly after it closes. In Amsterdam the start is 14:00 in the European summer and 13:00 in the winter.

How often is the GDT auction held?

Twice a month, on the first and third Tuesday. GDT also runs smaller Pulse auctions in between, for a few products such as whole milk powder and butter.

What is the GDT Price Index?

It measures how much prices changed since the previous event, as a weighted average of the percentage price changes. Only winning prices that rose above their starting price count in the calculation.

Why does a dairy auction move the New Zealand dollar?

Because dairy is a large part of what New Zealand sells abroad: milk powder, butter and cheese were 30% of goods exports in 2025. Higher prices mean more export income and higher payouts to farmers.