Southwest Airlines (NYSE:LUV) has implemented a shareholder rights plan, commonly known as a "poison pill," following pressure from activist investor Elliott Investment Management.

The announcement came on Wednesday as the airline looks to protect itself from potential hostile takeover attempts.

The newly adopted poison pill will see the company issue one right for each share of common stock.

These rights will initially trade alongside the carrier's common stock but will become exercisable if any person or group acquires 12.5% or more of Southwest's shares.

The move is aimed at diluting the stock and making a takeover more challenging.

Elliott Investment Management, known for its aggressive tactics in pushing for corporate changes, was not immediately available for comment following Southwest's announcement.