Spirit, which filed for bankruptcy protection last year, says it has rejected the new Frontier overture but would be open to a higher offer. Spirit, which filed for bankruptcy protection last year, says it has rejected the new Frontier overture but would be open to a higher offer. Spirit Airlines, Frontier Airlines Inc, Airlines and Airplanes, Mergers, Acquisitions and Divestitures, Travel and Vacations, Stocks and Bonds, Bankruptcies, JetBlue Airways Corporation, Antitrust Laws and Competition Issues, United States, Discount Selling, Prices (Fares, Fees and Rates), Private Equity, Indigo Partners LLC NYT > Business