(Reuters) -Spirit Airlines is in constructive discussion with its creditors and continues to explore strategic alternatives to improve liquidity, the ultra-low-cost carrier said on Tuesday. The negotiations, with a supermajority of the noteholders, have remained productive, advanced materially and are resuming in the near term, it added.

Spirit Airlines Inc. is preparing to file for bankruptcy protection after merger talks with Frontier Group Holdings Inc. broke down, the Wall Street Journal reported.

Spirit Airlines is preparing to file for bankruptcy protection after merger talks with Frontier Airlines broke down, the Wall Street Journal reported, citing people familiar with the matter. Shares of the company were down 39% at $1.8 after the bell. The stock has fallen nearly 80% this year, while the S&P 500 passenger airlines index jumped 52%.