Hawaiian Holdings (HA) shares rose 6% in intraday trading on Wednesday after the parent company of Hawaiian Airlines agreed to an extension of the U.S. Department of Justice’s review period for its proposed acquisition by Alaska Air Group (ALK).

Hawaiian and Alaska Air said they would “continue to cooperate” with the Department of Justice during the review process, with the deadline extended by 24 hours to 12:01 a.m. Eastern Time on Friday, according to a filing with the U.S. Securities and Exchange Commission (SEC).

Review period nears finish line amid antitrust issues

The $1.9 billion deal, which caused Hawaiian’s shares to nearly triple in value when it was first announced last December, was delayed because the U.S. Department of Justice initially requested additional information in February to assess the antitrust implications of the merger.

Both sides said they certified “substantial compliance” with the demands in May, beginning a 90-day review period that was originally scheduled to end on August 5 before the merger could be completed. The review period has now been extended twice, first to August 15 and then again when the companies agreed to an extension until Friday.

The Biden administration has taken a particularly close look at mergers in the airline industry, raising concerns that some major airlines had become too powerful and taken away choice from customers. Antitrust investigations and lawsuits led JetBlue Airways (JBLU) and Spirit Airlines (SAVE) to call off their own merger earlier this year.

Hawaiian shares rose 6.3% to $14.94 as of 10:45 a.m. ET on Wednesday, while Alaska Airlines shares fell 1.2% to $35.05.