JetBlue Airways Corp. is flying a new course after its move to acquire Spirit Airlines, Inc. was nuked by a federal judge last month.

News hit late Monday that activist investor Carl Icahn has acquired 9.91% of the low-cost carrier, sending shares up more than 14% in premarket trading in New York. 

As explained in a filing, Icahn believes JetBlue is "undervalued and represented an attractive investment opportunity." 

The filing continued: "The Reporting Persons have had, and intend to continue to have, discussions with members of the Issuer's management and board of directors regarding the possibility of board representation." 

In recent years, JetBlue has lost money and experienced operational challenges. The new CEO, Joanna Geraghty, who assumed her position on Monday, has committed "aggressive action" to guide the airline out of financial turbulence and into blue skies of profitability.

A spokesperson for JetBlue told Barron's: 

"We are always open to constructive dialogue with our investors as we continue to execute our plan to enhance value for all of our shareholders and stakeholders."

Icahn's move comes one month after JetBlue's failed takeover of Spirit Airlines following US District Judge William Young's decision to side with antitrust enforcers (Biden administration), arguing that a merger would suppress competition. Spirit has since explored restructuring options. 

As for the billionaire, this is his first public activist campaign since research firm Hindenburg Research took aim at his publicly traded firm, Icahn Enterprises, alleging it was overvalued and held assets at inflated prices. 

Icahn's history in the airline industry includes the time he seized control of faltering TWA in 1985 and dumped assets. After years of turmoil in