The asset beta is used to calculate the cost of financing milk processing operations, and in turn affects the milk price Fonterra pays its farmers.
It reflects the extent to which the assets associated with processing milk are more or less risky than the stock market as a whole.
"We acknowledge that estimating the asset beta with reliability and confidence is difficult. However, after considering all available information, including submissions on the independent report we released in April on the subject, our emerging view is that Fonterra' asset beta of 0.38 is not practically feasible," Begg said.
Begg acknowledged that there are differences between the risks borne by Fonterra and other comparable producers.
"However, based on the evidence we have, we do not consider the differences in the risks are sufficiently material or relevant to justify using an asset beta of 0.38," she said.
The purpose of the milk price monitoring regime is to incentivise Fonterra to operate efficiently while providing for contestability in the market for the purchase of farmers' milk. The regime exists because there is not a competitive market for the purchase of farmers' milk because of Fonterra's near monopoly.
The regime also provides transparency of information about how Fonterra sets the farm gate milk price and gives independent processors greater confidence that the price reflects market prices for commodities and efficient costs of collecting and processing milk.
Under the regime, the Commission must review Fonterra's Milk Price Manual and the base milk price calculation each dairy season.
In a supplied statement, Fonterra said it would be submitting its response to the Commission on the matter. "The Co-op stands by its view that the cost it attributes to its assets is accurate and this view is backed by independent expert analysis," it said.
Fonterra's forecast for the current season is $7 per kg of milksolids, up from $6.75/kg in 2017/18.
-- Staff Reporter