** Shares of New Zealand's a2 Milk ATM.NZ down ~3% to NZ$7.91, set for worst week since mid-April with a drop of more than 11%

** Milk producer said earlier this week it was recalling three batches of its a2 Platinum infant milk formula sold in the U.S. after testing detected cereulide, a toxin associated with foodborne illness

** Co said no illnesses have been reported and it is working with the U.S. Food and Drug Administration on the issue

** Stock down 26.6% YTD