Shares of JetBlue Airways (JBLU) gained in double digits in after market trading on Feb 12. The upside followed a stake-related disclosure by activist investor Carl Icahn. Per a SEC filing, Icahn currently has a 9.91% stake in JetBlue.Justifying his decision to buy a stake in the low-cost carrier, Icahn said that he believed JBLU shares were undervalued and represented an “attractive investment opportunity". Icahn intends to continue discussing with management and board of directors regarding the possibilit ...