Pfizer's merger collapse prompts speculation it will seek new takeover

$160bn tie-up with Allergan, which would have been world's biggest pharmaceutical deal, scuppered by US tax crackdown

Barack Obama's derailment of Pfizer's $160bn (114bn) merger with Allergan sparked immediate speculation on Wednesday that the US drugs company would turn its attention to another big pharmaceutical takeover.

Pfizer, best known for Viagra and its cholesterol pill Lipitor, will pay the Botox producer Allergan $150m for pulling out of what would have been the world's biggest healthcare deal, first announced in November and now abandoned after the US Treasury Department stunned financial markets with measures to clamp down on tax efficient mergers and takeovers.