Key Takeaways Spirit Airlines has rejected a renewed offer from Frontier Airlines, instead opting to continue with its bankruptcy restructuring.The sides detailed new communications from the last several weeks in SEC filings on Wednesday.

Spirit Airlines rejected a $400 million merger proposal from Frontier this week, saying the offer was financially inadequate and came too late. Spirit Airlines declined an opportunity to merge with rival low-cost airline Frontier on Wednesday.

Frontier Airlines is making another offer to merge with bankrupt Spirit Airlines, less than two years after a previous plan fell through.