Activist shareholder Elliott Investment Management is attempting to remove Southwest Airlines’ CEO after purchasing a $1.9 billion stake in the carrier, which has experienced operational and financial difficulties.

Monday morning’s trade saw an 8% increase in the airline’s shares.

The investment firm bemoaned the more than 50% decline in Southwest’s stock price over the previous three years in a letter to the board.

According to the company, Southwest’s inability to adapt has harmed its capacity to compete with other carriers. It claimed that the Dallas-based airline’s widespread flight cancellations in December 2022 were caused by antiquated software and operating procedures.

The investment group stated in the letter dated Monday that “poor execution and leadership’s stubborn unwillingness to evolve the Company’s strategy have led to deeply disappointing results for shareholders, employees, and customers alike.”

Robert Jordan, the CEO, “has delivered unacceptable financial and operational performance quarter after quarter,” according to Elliott. Jordan and Gary Kelly, the airline’s executive chairman and former CEO, “are not up to the task of modernizing Southwest,” according to the statement.

Elliott contacted Southwest on Sunday, the business said, and it looks forward “to better understanding their views on our company.”

“The CEO and management have the confidence of the Southwest Board of Directors to carry out the company’s strategic plan, which aims to generate long-term value for all shareholders, provide safe and dependable customer service, and fulfill our obligations to all stakeholders,” a spokesperson said in a statement.