Fonterra's latest auction of dairy products has shown a decline in prices for a second month.
Fonterra says the average selling price for all products fell 3.5% to $US3880 per tonne in May.
Global dairy trade manager Paul Grave sees it as a market adjustment to exchange rate movements and increased supplies.
Whole milk powder prices declined 3.6% to $US3790 per tonne.
However, prices for anhydrous milk fat, rose by almost 6%.
Mr Grave says sales through the monthly on-line trade have been growing: $138 million worth of product was sold on Tuesday night.
Last week, Fonterra forecast a higher payout for next season due to stronger demand in Asia and limited global supply.