Massive Irish pharma deal in doubt after tax inversion clampdown

Shares in one of Ireland's largest pharmaceutical firms have plummeted amid a crackdown on US companies relocating overseas for tax purposes - know as tax inversion.

Allergan, which is based in Dublin, had been expected to merge with Pfizer of New York, which would move its HQ here, to take advantage of our lower corporate tax rate.

However, under the new rules the deal may not be as beneficial and both companies say they are now reviewing the plans.

The merger was formally announced last November.