Pfizer's $106 billion bid for AstraZeneca this year was partly motivated by tax reasons – and met strong protests from U.K. lawmakers following lobbying from AstraZeneca.
However, Shire is already based overseas for tax purposes, and employs a few hundred people in the U.K., less than a tenth of its global workforce. In contrast, AstraZeneca still had a substantial manufacturing base in the U.K. and employed close to 7,000 people.
Shire is based in Dublin for tax purposes, and buying it may also enable AbbVie to take advantage of a "tax inversion" by spending overseas revenues rather than bringing them back to the U.S. to be taxed.
If AbbVie is successful, it plans to create "a new US listed holding company with a UK tax domicile," according to a statement from Shire.
The U.S. company has made three proposals since early May: The first at £39.50 per share; the third and most recent at £46.26, in a mixture of cash and AbbVie shares. Both represent a substantial premium to the share price of £37.38 at the close of Thursday. The final deal would have valued the group at some £27 billion ($46 billion).