AbbVie, the Chicago pharmaceutical giant trying to buy out Shire, got a costly flip-flop instead of an inversion this week after U.S. government rule changes prompted AbbVie leaders to change their mind about acquiring the British-registered Shire to pay less in taxes.

Shire, which operates its U.S. business out of Wayne, will receive $1.64 billion in compensation for the failed takeover, according to a Bloomberg Businessweek report. After several prior attempts, Shire had finally agreed to a $55 billion deal in July.

Until more recent law changes limited the conversion of foreign cash to U.S. loans and tightened ownership rules for U.S. shareholders.

“The unprecedented unilateral action by the U.S. Department of Treasury may have destroyed the value in this transaction, but it does not resolve a critical issue facing American businesses today,” AbbVie Chairman and CEO Richard A. Gonzalez said in the article, advocating for tax code reform in order to put foreign competitors at a disadvantage rather than an advantage.

Read more about the breaking news in Bloomberg BusinessWeek here, and check out previous Chesco Business Today coverage of the takeover attempt here.