MIAMI — Alaska Air Group and Virgin America have received a request for additional information from the Antitrust Division of the United States Department of Justice (DOJ) in connection with Alaska’s proposed acquisition of Virgin America.

The two carriers said the so-called “second request,” is a “standard part” of the DOJ review process. Such information request extends the period that both parties must wait to close the transaction, until 30 days after they have fulfilled the request or if the waiting period is otherwise terminated by the DOJ.

The parties further commented that the response would be expedited, and are confident that the DOJ will grant the required regulatory approval to complete their transaction before January 1, 2017.

The proposed acquisition is also subject to approval of Virgin America’s shareholders in addition to the satisfaction of other customary closing conditions, including expiration or termination of the waiting period under the Hart-Scott-Rodino Act, which provides that the parties must not complete certain mergers, acquisitions or transfers of securities or assets, until they have made a detailed filing with the U.S. Federal Trade Commission and the DOJ, which will determine whether the transaction will not affect U.S. commerce under the antitrust laws.

In early April, Alaska Airlines Group announced a $2.6 billion offer to acquire Virgin America. The emerging airline would become the 5th largest carrier in the United States in terms of capacity (available seat miles), just ahead of JetBlue Airlines. The merger would provide Alaska a larger presence in the West Coast, particularly in California, which is to date the nation’s largest market and three times the size of Oregon, Washington and Alaska combined.