Pfizer said on Wednesday it will spin off its majority stake in animal health business Zoetis to shareholders by allowing them to swap Pfizer stock for Zoetis shares at a 7% discount.

Pfizer, the largest U.S. drugmaker, sold Zoetis shares in an initial public offering in February that raised $2.2 billion. Pfizer retained an 80% stake in Zoetis after the IPO and now plans to unwind that, starting with this offer.

The move comes as Pfizer continues to unload its non-pharmaceuticals businesses to focus on its core prescription drugs business, which has far higher profit margins.

The offer would allow Pfizer shareholders to exchange $100 worth of company stock for $107.52 worth of Zoetis stock. The premium is meant to encourage Pfizer shareholders to acquire Zoetis shares.

Pfizer owns 400,985,000 shares of Zoetis Class B common stock that it will convert to Class A shares for the exchange. Pfizer shareholders must request at least 160.4 million shares of Zoetis common stock for the exchange to take effect.

Pfizer said that selling the rest of Zoetis will boost earnings starting in 2014. If it does not sell all of its stake through the exchange offer, Pfizer said it could turn to additional exchange offers or a special dividend.

Zoetis shares were priced at $26 in the February IPO and closed their first day of trading at $31.01.

In April 2012 Pfizer sold its infant nutrition business to Nestle for $11.9 billion. The drugmaker has said it plans to use cash from asset sales to aggressively buy back its shares.

Last month Pfizer said it had repurchased $6.3 billion of stock this year and was authorized to spend another $5.5 billion on buybacks.

Meanwhile, the company is considering whether to sell off its wide array of generic prescription drugs, which it calls "established products." In that event, the company would keep its branded patent-protected medicines.

Chief Executive Ian Read in April said Pfizer would need three years to evaluate whether to spin off the generic medicines.

JPMorgan Chase, Bank of America, Goldman Sachs & Co and Morgan Stanley are managing the exchange offer. Skadden, Arps, Slate, Meagher & Flom is advising Pfizer.