This could kick off a takeover battle for Shire, a perennial takeover target. It initially built a niche with amphetamine-based drugs to treat ADHD, but has used the revenues from these treatments to expand into lucrative orphan diseases and specialty pharmaceuticals. U.S. based AbbVie, which was spun out of larger Abbot Laboratories last year, now has until July 18 to make a full and final offer.
Shire has previously stressed the importance to it of remaining independent. Flemming Ornskov, its chief executive who started at the company last year, has pursued an aggressive acquisitions policy, and the company expects to more than double its 2013 annual product sales to US$10 billion by 2020.
AbbVie is advised by JPMorgan, while Shire is advised by Citi, Evercore and Morgan Stanley.
- By CNBC's Catherine Boyle