Shares of pharmaceutical company Affymax Inc. jumped Wednesday after a pair of analysts upgraded the stock, citing its development pipeline and future prospects in the anemia treatment market.

Affymax shares rose $1.89, or 5.7 percent, to $34.89 on the Nasdaq in midday trading. The stock has traded between $29.30 and $37.20 since going public Dec. 15. It debuted at $30.

RBC Capital Markets analyst Jason Kantor initiated coverage at "Outperform" with a $44 price target, citing the company's focus on the EPO market. That price target implies growth of 33.3 percent over the stock's closing price Tuesday of $33.

EPO is short for erythropoietin, a natural protein that stimulates increased production of red blood cells. The anemia treatment market was worth an estimated $11.5 billion in 2006, up from $10.8 billion in 2005.

"The (EPO treatment) market for anemia is the largest and most lucrative market in biotech," Kantor wrote in a note to investors.

The drug under development, called Hematide, provides once monthly dosing versus competitor Amgen Inc.'s Epogen and Aranesp, with between a once-weekly and once every three weeks dose, Kantor said. The company has already reported positive data from a Phase II clinical trial.

Cowen and Co. analyst Phil Nadeau initiated coverage with an "Outperform" rating, also citing the sales potential for Hematide.