The US Justice Department has approved the merger of United (UAUA) and Continental (CAL), the two airlines. The merger is expected to close on October 1.

Surprisingly, the approval has come in less than four month's time as it is said that after the merger the new company will be largest airline in the world.

Moreover, it also seems that a deal between low-cost carrier, Southwest (LUV) and the two airlines to give access to Newark Airport has also played a key role in getting the approval.

Within two hours of the announcement of the two parties about their merger, the Justice Department also announced that it has completed its Hart-Scott-Rodino Act review and that it has done its investigation and closed the pending approval.

After this, the next step is to get the shareholders' approval by both the airlines. Said United CEO Glenn Tilton, in a prepared statement that they are expecting to get that confirmation as well and after that they will end the deal by October 1.

Adding to that, Continental CEO, Jeff Smisek said that the Justice Department approval has cleared one of the biggest hurdles.