Another hit for AbbVie: Unexpected $673M Irish tax bill adds to Allergan merger woes

Sealing an eight-figure merger is no laughing matter: Just ask AbbVie and Allergan, two drugmakers fighting through regulatory hurdles to consummate their $63 billion deal.

Just weeks ago, U.S. antitrust regulators made a second request for information on the deal, which is generally a sign that merger partners will need to make changes—such as selling off assets—to win approval.