TRENTON, N.J. (AP) — Drugmaker Pfizer Inc. plans to try to sell its controlling stake in its former animal health business, Zoetis Inc., through a voluntary stock exchange with Pfizer shareholders.

Pfizer, the world’s second-largest drugmaker, said Wednesday that its shareholders will be able to trade their Pfizer holdings for Zoetis shares at a discount expected to be about 7 percent. The discount level will depend on the average price of both stocks in the three days leading up to the offer’s expiration, after the stock market closes on June 19.