"We are obviously pleased with today's bankruptcy court approval," said Southwest Chief Executive Gary Kelly, in a news release. "We have enjoyed working with the ATA people, and we look forward to getting started on our code-sharing early next year. I extend my congratulations to ATA as it begins its restructuring process."
ATA filed for Chapter 11 bankruptcy protection in October. The court recently oversaw an auction for some or all of the carrier's assets.
Southwest won by offering a total of $117 million in cash and financing in exchange for six of ATA's Chicago Midway airport gates and a hangar.
As part of the deal, the two airlines will have a code-sharing arrangement, making travel easier for passengers.
Southwest shares were up 17 cents, or 1.1%, at $15.75.