Over the weekend, Fonterra, the world's biggest dairy exporter, revealed contaminated New Zealand-made whey protein concentrate had been exported to China, Malaysia, Vietnam, Thailand and Saudi Arabia and used in products including infant milk powder and sports drinks.
The price of the units fell 8.7 percent to a low of NZ$6.55 each at the start of trading.
The food scare also prompted a slide of close to 1.5 percent in the New Zealand dollar against most major currencies.
