Southwest Airlines raised its third-quarter revenue forecast, authorized $2.5 billion in share buybacks and announced a slew of changes to its business as it continues to face pressure from activist hedge fund Elliott Investment Management.

Elliott Investment Management told shareholders Tuesday it is ready to go to a proxy fight with Southwest Airlines.

The moves away from Southwest’s simple business model and quirky traditions come as airline management faces pressure from activist investor Elliott Investment Management. The hedge fund blames management for Southwest’s recent underperformance compared with its closest rivals, and wants to replace Jordan and most of the Southwest board.