Halliburton and Baker Hughes announced a four-month extension for their $35 billion stock-and-cash merger on Tuesday, pushing the deadline to April 30. The merger's announcement, made in November 2014, was originally scheduled to end in January 2016 and would have united the nation's second and third largest oil field services provider, signaling energy consolidation amid falling oil prices, according USA Today.

Over the past year, the two companies had engaged in various discussions with the Department of Justice regarding the deal. Both parties responded to "numerous DOJ requests for information," and reportedly produced "millions of pages of documents" in response to specific questions, which the two believed were more than enough to address competitive and antitrust concerns.

"Both companies strongly believe that the divestiture package, which was significantly enhanced to address the DOJ's specific competitive concerns, is more than sufficient to address concerns raised by competition authorities, including the DOJ," the firms said in a statement. 

However, the companies were forced to extend after they received notification from the Department of Justice that stated the submitted divestiture proposals aimed at remedying antitrust concerns were insufficient.

Going forward, the two companies intend to continue discussions with the DOJ with the hope of completing the transaction as soon as possible. Furthermore, they're working to resolve any lingering concerns of the European Commission whose preliminary scrutiny is set to end on Jan. 12, according to CNBC.

Despite the extension and ongoing plans, the firms cautioned that there is no guarantee that an agreement with the DOJ or any other competition authorities will be reached.

Both companies stocks came to a roughly 15-minute halt in trading after they made the announcement Tuesday, before reopening again at around 3:10 p.m. EST.