Irish pharmaceutical producer Shire has made an offer to buy US drugmaker Baxalta for around $30 billion in stock. With the bid, Shire is said to be trying to solidify its position in rare disease treatments. Deerfield, Illinois-based Baxalta, spun off from Baxter International Inc. in July, specializes in bleeding disorders. 

Dublin-headquartered Shire makes treatments for a range of conditions including attention deficit hyperactivity disorder, epilepsy and hunter syndrome. It said the combination with Baxalta would create a global leader in rare disease drugs with $20 billion in sales by 2020.

In a statement dating from mid-July, Shire urged Baxalta to engage in negotiations. The company said it offer implies a value of $45.23 per share, a 36% premium.