China’s surging demand for blood products is drawing the world’s largest suppliers, including Barcelona-based Grifols SA, which is in talks for a possible $5bn transaction that would be its second acquisition in the country this year.

The world’s biggest maker of immunoglobulin is negotiating to buy a stake in Shanghai RAAS Blood Products Co., the companies said last week in separate statements. If completed, it would give Grifols with a major stake and involves integrating the Spanish company’s U.S. unit that’s valued at $5bn with Shanghai RAAS in exchange for newly issued shares, according to the statements.

Demand is climbing for human serum albumin, a blood plasma derivative used to treat liver diseases in China, where supplies are limited by strict rules governing blood donation. The talks announced Nov. 22 follow an agreement Grifols signed in May to invest 50m euros ($57m) in Chinese blood products manufacturer Boya Bio-Pharmaceutical Group Co. and open plasma collection centers in China.

“Foreign blood products companies regard China as a strategic market, and they are expected to continue to strengthen in areas such as resource input and business footprint,” said Yang Song, a pharmaceutical industry analyst at Guotai Junan Securities Co. in Shanghai.

Grifols shares rose 0.7 percent as of 9:33 a.m. local time, bringing their gain this year to 6.4 percent.

Grifols’ Australian rival CSL Ltd. has expanded its foothold in the Chinese market, paying $352m last year for a majority stake in Wuhan Zhongyuan Ruide Biological Products Co., which operates plasma collection centers. CSL acquired the rest of the company in June for another $102m.

China does not allow imports of most blood-derived products except for albumin. Chinese use 420 tons of the protein annually, the Xinhua News Agency reported last year, and 60 percent of that comes from imports.

In the proposed Shanghai RAAS deal, Grifols would integrate its unit from the U.S., the world’s largest economy and the biggest exporter of blood.

There were 627 collection centers in the U.S. in 2017, up 23 percent from the previous year, according to a research report by CLSA published in August. Those U.S. centers collected about 42 million liters of plasma last year, 44 percent more than 2013, according to data from the Plasma Protein Therapeutics Association.

CSL has 26 percent of the global plasma-collection market, compared with 21 percent for Grifols and 20 percent for Lexington, Massachusetts-based Shire PLC, according to CLSA.