Frontier Group Holdings (ULCC) shares soared 16.4% in the last trading session to close at $5.81. The move was backed by solid volume with far more shares changing hands than in a normal session. This compares to the stock's 29.6% gain over the past four weeks. This jump in stock price came after news that Spirit Airlines (SAVE) , a Frontier Group Holdings rival in the low-cost airline space, is considering bankruptcy. Spirit has faced losses and declining revenue due to fierce competition and the failed at ...