Overall, prices were effectively unchanged in this week's GlobalDairyTrade auction. There was a 0.3% lift, which reaffirmed ASB's 2017-18 forecast of $6.75.
It was the seventh consecutive auction that had a smaller than 2% movement in either direction, as the lower volatility continued.
Milk-fat prices were strong: butter and anhydrous milk fat lifted 3.8% and 3.6% respectively.
Butter reached its second-highest level in GDT auction history and another butter price surge might not be far away, Mr Penny said.
Whole milk powder products fell 1.6%, whereas futures pricing ahead of the auction had pointed to a 3%-5% price rise.
That down-side surprise continued a recent pattern of futures pricing overestimating the auction result, he said.