Just days after the U.S. Department of the Treasury and President Barack Obama introduced new measures to fight tax inversion, the deal that would have been the biggest pharmaceutical acquisition in history is no more.

Drug companies Pfizer and Allergan said earlier today that the planned $150 billion merger that they announced last year has been canceled. In a press release, Pfizer said the decision was fueled by the recent crackdown, calling it an “adverse tax change.”

The treasury took two new steps on Monday to fight loopholes that allow companies to take advantage of certain tax strategies.

First, it will limit benefits foreign companies get when acquiring a multiple U.S. corporations. Now multinationals who acquire multiple American corporations through stock-based transactions will not be allowed to use their size to circumvent current inversion limits.

Second, the Treasury will take on what is known as “earnings stripping,” where companies reduce the taxable U.S. profits of the foreign company through a series of financial calisthenics.

Essentially, the U.S. subsidiary of a foreign firm will get an internal loan from its parent and is able to deduct interest payments from this loan from its overall earnings. This will effectively reduce the amount of money the U.S. Government gets from the subsidiary's profits.

When it comes to “earnings stripping,” the treasury focus on companies using those financial strategies if they are not financing new investments in the country.

Tax inversion has become a hot topic in Washington as the Obama administration continues to criticize U.S. companies that move their tax domicile to countries with lower corporate tax rates through international mergers or acquisitions.

"We should keep building an economy where everybody has a fair shot, and everybody plays by the same rules." —@POTUS https://t.co/JO8R1vDCEF

— The White House (@WhiteHouse) April 5, 2016

The Pfizer-Allergan merger was on which received a lot attention due to its size. Though the recent measures did not call out the companies this specific deal, Obama has called on Congress to take action to stop the practice by passing definitive tax reform to cover these kinds of loopholes.    

Last month, Philadelphia City Council President introduced legislation that would prevent city government from doing business with companies fleeing the country for “tax havens” abroad.