Allergan and Pfizer Call Off Proposed $160B Merger

Allergan and Pfizer Call Off Proposed $160B Merger

Top U.S. drugmaker Pfizer and Irish rival Allergan are charting independent futures after scrapping a record $160 billion deal torpedoed by new Treasury Department rules meant to block American companies from moving their corporate addresses overseas — on paper — to avoid U.S. taxes.

The rules issued Monday, aimed at stopping the companies' "tax inversion" deal, wiped out its financial incentives and rationale for Pfizer Inc., although they had no impact on Allergan PLC.

That led Pfizer and Allergan to walk away "by mutual agreement" on Wednesday. Pfizer, based in New York, will pay Allergan $150 million as reimbursement for its deal-related...