ToplineHedge fund billionaire Carl Icahn reported a near 10% stake in JetBlue on Monday and said the airline’s stock was undervalued, according to a filing, rocketing the company’s stock up as high as 19% in after-hours trading—weeks after JetBlue’s plans to merge with rival Spirit Airlines were blocked by a federal judge.An Airbus A320 passenger aircraft of JetBlue airlines arrives from Tampa at JFK International ... [+] Airport in New York as the Manhattan skyline looms in the background on February 7, 20 ...