Pfizer Inc and Allergan Plc are in final stages of talks over an all-stock deal, CNBC tweeted, citing sources.

Reuters had already reported that Pfizer’s talks to acquire Allergan had accelerated, as the US Treasury prepares to clamp down further on tax inversions.

Pfizer will offer more than 11 shares for each Allergan share held, CNBC said yesterday.

The offer would value Allergan at at least $366.41 per share or a total of more than $144 billion. The deal would result in Pfizer domiciling in Ireland.

The Treasury this week will clamp down further on tax-avoiding ‘inversion’ deals done by US companies with foreign rivals, according to a letter obtained by Reuters on Wednesday.

Pfizer shares were down 1.6 per cent in early trading, while Allergan’s were down 1.8 per cent.

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