Yesterday, animal health business Zoetis (NYSE:ZTS) announced it would be pricing over 86 million shares of Class A common stock at $26 per share, a price higher than its original $22-$25 range. The IPO began trading today, and raised more than $2.2 billion for the former Pfizer (NYSE:PFE) division. Even after today's IPO, which is the biggest in the U.S. since Facebook's last May, Pfizer will retain a substantial ownership stake -- 83% -- in the newly public company. Pfizer could give up an extra 3% of the company to underwriters, should they choose to exercise certain options.

Zoetis, which has a 60-year history under Pfizer, makes vaccines for both farm and companion animals, and has operations in about 70 countries worldwide. The market was able to support the pricing at the higher $26 level with ease; shares closed nearly 20% higher today, finishing at $31.03.

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