The dairy industry says it's too early to talk about the financial impact from threats to contaminate infant formula and other products.
Two packages of formula laced with 1080 poison were sent to Fonterra and a farmer group last November.
Fonterra chief executive Theo Spierings said the industry would not tolerate blackmail and its focus was on assuring customers and consumers that its products were safe, and to catch the person or people involved.
Tatua Cooperative Dairy chief executive Paul McGilvray agreed, and said it was a despicable act.
Fonterra and Tatua have beefed up testing and security in response.
Fonterra Shareholders' Fund fell 5 cents to close at $5.80 yesterday, while Fonterra Co-operative Group's fell 7 cents to $5.80.
Some analysts said the main risk was the potential for a short term temporary ban on dairy imports from trading partners.