Spirit Airlines' latest bankruptcy filing has Wall Street tapping its rival to flourish. Frontier Airlines' share price jumped 14.5% on Tuesday, as Deutsche Bank analysts upgraded the stock to a "Buy" rating. They also doubled their 12-month price target from $4 to $8. The stock last closed trading at $5.61. Deutsche Bank's Michael Linenberg wrote that Frontier is "best-positioned to be the biggest beneficiary of Spirit's bankruptcy" because it competes the most with the struggling budget airline.