Pfizer Inc. and Allergan PLC terminated their planned $150 billion merger after the Obama administration took aim at the deal that would have moved the biggest drug company in the U.S. to Ireland to lower its taxes.

Pfizer will pay Allergan a breakup fee of $150 million. The breakup fee is relatively small, especially given Pfizer’s market value of some $200 billion.

The Wall Street Journal reported Tuesday that Pfizer’s board had voted to halt the combination and the New York-based pharmaceutical company then notified Dublin-based Allergan.

The decision to walk away is the latest setback in Pfizer’s long-running efforts to overcome what Chief Executive Ian Read has said was the company’s competitive disadvantage with foreign rivals that faced significantly lower tax bills.

In addition, the failed deal also hurts Pfizer’s plans to break itself up. Company executives have considered splitting the company for years, but they have been deterred by concerns that its businesses may not be large enough to stand alone. The Allergan deal was seen as building the Pfizer’s strength in both high-cost, high-growth drugs as well as older, lower-cost drugs.