Pfizer Inc. (NYSE:PFE) has been in talks to acquire the Swedish rare disease specialists Sobi. Sobi has an estimated worth of $4.3 billion. The company specializes in rare conditions and has had previous deals with Pfizer. The deal, however, is being kept a secret; therefore not all details are available.

During the last earnings call, Pfizer CEO, Ian Read, had hinted at potential acquisitions to expand the company’s portfolio. He also pointed out that there are a lot of potential acquisitions out there, but his company will only target those with long term potential. Additionally, Pfizer is already the distributor of the company’s hemophilia treatments. Sobi is also seriously considering the proposal, as it postponed its shareholder meeting in light of recent developments.

Pfizer has already acquired Hospira Inc for $15 billion and has a new rare disease research unit. This indicates that the company is looking at drugs that have long term potential and can give high returns on investment. The company is also targeting the giant British pharmaceutical company GlaxoSmithKline. This would be the second time that Pfizer goes for a British pharmaceutical giant, the first being the failed attempt at AstraZeneca last year.

The failed deal had given rise to concerns that AstraZeneca, being so large, would result in heavy job losses on both sides of the Atlantic. Pfizer had, however, put up a competitive offer of £69 billion, compared to the company’s value of $90 billion. AstraZeneca refused all four offers and it seems like the new deal would also raise similar concerns. GSK is an even larger company than AstraZeneca, employing 115,000 workers, compared to Astra’s 50,000. Pfizer has been reporting a significant increase in profits, but as its Viagra patent runs out of time, the company desperately needs a new lead. Analysts believe that the Sobi acquisition makes the stock a buy, but are unsure about GSK.