Shire Pharmaceutical shares soar on rejected AbbVie bid

Shire Pharmaceuticals is known primarily as a maker of drugs to treat rare diseases

Shares in British pharmaceutical firm Shire soared as much as 13% after the company rejected a third takeover bid from US drug giant AbbVie.

AbbVie had offered £27bn ($46bn) for Shire, which is known primarily as a maker of drugs for rare diseases.

Shire said the bid undervalued the firm and would deny shareholders future growth benefits.

It also warned about efforts by AbbVie to purchase the firm solely because of its attractive tax base in Ireland.

"The Board also had concerns regarding the execution risks associated with the proposed inversion structure, as AbbVie would redomicile in the UK for tax purposes," wrote the firm in a statement announcing its decision.

Founded in 1986 in the UK, Shire conducts the majority of its business in the US. It changed its tax base to Ireland in 2008.

Shire had rejected two other bids from AbbVie. The firm is seen as an attractive takeover target for US drug firms because it has no single controlling shareholder.

AbbVie is just one of several US firms looking to acquire companies in favourable tax locations and then relocate in the lower-tax nation, in a process known as an inversion.

US drug giant Pfizer recently failed in its efforts to do something similar with British firm AstraZeneca after the proposed acquisition was met with hostility from both US and UK lawmakers.