Pharmaceutical giant Pfizer (PFE) announced Thursday it is considering selling its animal health and baby food units in hopes of appeasing shareholders' demands.

The powerful drug making company could be either selling or spinning off the two units, which could ultimately be worth up to 20 billion, to be able to focus more on its other properties. The company is expected to evaluate both options at length and might not make a decision for up to two years, according to a Pfizer spokesman.

Pfizer has long been expected to either sell or spin-off some of its properties, especially ahead of the loss of its patent on Lipitor. The animal health unit had 3.6 billion dollars in sales in 2010 and the baby food unit had 1.9 billion, combining to account for about eight percent of Pfizer's total sales.

The actions we're announcing today are driven by the potential to create value for shareholders and enable Pfizer to become a more focused organization, better positioned for future success, said Ian Read, president and chief executive officer of Pfizer.

While selling properties worth up to 20 billion dollars would appease a lot of smaller company's shareholders, some industry experts were upset the company didn't include other units into consideration.

Sanford Bernstein industry analyst Tim Anderson, for instance, had speculated in March that Pfizer could diversify up to 40 percent of its properties, a whopping number compared to the proposed 8 percent. Those numbers undoubtedly raised expectations for disappointed shareholders as Pfizer's stock price dropped about 2.6 percent to $20.24 during today's trading at time of closing.

This consideration to sell off properties is the second one in recent months. In April, the company sold its capsule making company, Capusgel, to private equity firm Kohlberg Kravis Robert & Co. for 2.38 billion. There had been rumors that the company might also consider selling its established brands division, but Pfizer's press statement was clear that will not be happening soon.

The statement said that the company will continue enhance the value of its established products business and that the division is well positioned to capture the opportunities being created by the demographics and rising economic power within these markets.

It's unknown exactly who might be suitors for the two units, should Pfizer sell, but that hasn't stopped speculation. One potential candidate could be Eli Lilly and Co. which just completed a purchase of Johnson & Johnson's European animal health unit. Lilly had been aggressive in going after Johnson & Johnson's animal health unit, in part due to a patent loss of its own, and might go after Pfizer's successful unit.

JPMorgan Chase will advise the company on its animal health property and Morgan Stanley and Centerview Partners will take care of the baby food unit.