Southwest Airlines adjusts its summer revenue outlook and approves $2.5 billion in stock repurchases.

• On Thursday, Southwest Airlines updated its third-quarter revenue forecast and announced several modifications to its business strategy.
• Spirit Airlines' former leader, Bob Fornaro, will be added to the board of directors by the carrier.

On Thursday, DALLAS announced that it had raised its third-quarter revenue forecast and authorized $2.5 billion in share buybacks, while also detailing changes to its business model in an effort to counter activist Elliott Investment Management's influence.

The airline anticipates a 3% increase in unit revenue in the third quarter compared to the same period the previous year, which is an improvement from its earlier forecast of a potential decline of up to 2%.

Southwest Airlines announced that it would appoint Bob Fornaro, a renowned industry expert, to its board of directors. Fornaro has a long-standing relationship with Southwest, having served as CEO of AirTran, the airline Southwest merged with in 2011, and as a consultant to the airline after the merger.

On Thursday, Southwest executives will unveil their vision for the airline's future at its Dallas headquarters during an investor day presentation. Despite this, CEO Bob Jordan and other senior leaders are facing mounting pressure from Elliott, which has called for a leadership change at the carrier.

The airline's executives will attempt to persuade investors that they are on the right course to increase profits and revenue. Over the summer, the company made significant changes to its 50-year-old business model, including assigned and extra-legroom seats, which could potentially increase revenue.

Southwest maintained its policy of allowing customers to check two bags for free during its presentation on Thursday, stating that it results in market share gains despite potential revenue loss from bag fees.

Southwest announced that it would reduce its services in Atlanta next year and potentially lay off over 300 flight attendants and pilots from the city in an effort to save money.

Gary Kelly, the executive chairman and former CEO of Southwest, announced that he would step down by the end of next year. The mechanics' union of Southwest later demanded a leadership change at the top of the airline. Southwest did not immediately respond to the strategy presentation it released on Thursday.

— CNBC's Rohan Goswami contributed to this report.