Pfizer unit to float in the States

Pfizer’s animal health unit Zoetis yesterday filed for a $100m initial public offering as the largest US drugmaker narrows the focus on its core prescription drug business. Pfizer, which bought US rival Wyeth for $67bn in late 2009 to bolster its array of medicines, has developed few big-selling drugs of its own since impotence-treatment Viagra was introduced in 1998. J P Morgan, Bank of America Merrill Lynch and Morgan Stanley will underwrite the offering.