Barcelona-based Grifols has agreed to acquire the operations of a fellow maker of blood plasma products, Talecris Biotherapeutics in North Carolina, for $4 billion in cash, stock and debt. The acquisition will expand Grifols’ presence in the United States, giving the company control of about one-third of the market.

Both companies collect blood samples from healthy donors at centers across the country, from which blood plasma is used to create therapies for blood-related disorders. Plasma is the liquid component of blood that carries blood cells.