No-frills air travel pioneer Spirit Airlines filed for bankruptcy protection on Monday, after struggling with a long run of quarterly losses, a failed merger attempt and upcoming debt maturities.

Spirit, known for its bright yellow livery, is the first major U.S. airline to file for Chapter 11 since 2011.

It has not posted a full-year profit since 2019 and has been facing an uncertain future after the collapse of its $3.8 billion planned merger with JetBlue Airways in January.

Below is a list of events, starting with a long-drawn bidding war for the airline two years ago:

Feb. 7, 2022: Spirit Airlines, along with budget carrier peer Frontier Group Holdings, unveiled plans to create the fifth-largest U.S. airline in a $2.9 billion tie-up to tighten competition against traditional carriers.

April 5, 2022: JetBlue Airways made an unsolicited $3.6 billion bid for Spirit, snarling its merger plans with Frontier and starting a U.S. low-cost carrier battle.

May 2, 2022: Spirit board rejected JetBlue’s offer, saying it had a low likelihood of winning approval from government regulators on antitrust risks.

May 16, 2022: JetBlue launched a hostile all-cash takeover bid for Spirit Airlines, two weeks after the rejection of its earlier offer.

May 19, 2022: Spirit urged shareholders to reject a hostile bid by JetBlue, saying it was “a cynical attempt to disrupt” its merger with Frontier.

May 23, 2022: Spirit CEO Ted Christie said it is unlikely shareholders would vote against its proposed merger with Frontier, to remain a stand-alone entity if shareholders reject.

June 2, 2022: Frontier agreed to offer a break-up fee of $250 million in a bid to secure its $2.9 billion bid for Spirit.

June 28, 2022: Spirit again rebuffs JetBlue citing antitrust concerns, weeks after it raised an offer with higher break-up fee and new ticking fee, amounting to a $3.8 billion bid.

July 27, 2022: Spirit Airlines canceled its sale to Frontier Group Holdings after Spirit shareholders balked at supporting it, weeks after Frontier declined to further raise its bid, drawing curtains on the bidding war with JetBlue. JetBlue prevailed in the months-long bidding war for Spirit Airlines after the ultra-low-cost carrier accepted its $3.8 billion buyout deal.

Oct. 19, 2022: Spirit shareholders voted in favor of JetBlue Airways’ $3.8 billion takeover offer.

Dec 9, 2022: Spirit offered as much as a 43% cumulative weighted average pay raise to its pilots over two years.

Jan. 10, 2022: Pilots at Spirit voted to ratify the contract, which represents an economic gain of $463 million or 27% over the next two years for the pilots.

March 7, 2023: The U.S. Justice Department filed suit to stop JetBlue from buying Spirit, saying the planned merger “will lead to higher fares and fewer seats, harming millions of consumers on hundreds of routes.”

March 21, 2023: California, along with three other states, joined the U.S. Justice Department lawsuit aimed at preventing the JetBlue-Spirit deal.

Oct. 31, 2023: The Justice Department urged a federal judge to block the deal at the antitrust trial, arguing that the deal would lead to higher fares and fewer flights.

Jan. 16, 2024: A federal judge blocked the merger after agreeing with the Justice Department that the deal was anti-competitive and would harm ticket buyers.

Jan. 19, 2024: Spirit said it is looking at options to refinance its debt and is not considering restructuring, since its shares had been falling on investor concerns about its financial future after the DoJ decision.

Also said its deal to merge with JetBlue remained intact, with the two companies appealing the federal judge’s ruling.

March 4, 2024: JetBlue and Spirit scrapped their $3.8-billion merger agreement, with the low-cost carriers saying there was no path forward after a U.S. judge blocked the deal in January on anti-competition concerns.

April 8, 2024: Spirit announced a deal with Airbus to delay all aircraft deliveries scheduled from the second quarter of 2025 through 2026 and furlough 260 pilots, to boost cash.

July 1, 2024: Spirit appointed Fred Cromer as its new chief financial officer, a month after its previous CFO Scott Haralson left the airline to join car rental company Hertz Global Holdings as its finance chief.

July 30, 2024: Spirit Airlines unveiled plans to tap into a growing demand for premium travel, chasing high-margin revenue, to mitigate cost pressures and boost its earnings.

Oct. 22, 2024: The Wall Street Journal reported Frontier Airlines is exploring a renewed bid for Spirit Airlines.

Oct. 30, 2024: Spirit announced additional furloughs of about 330 pilots on Jan. 31, 2025, in efforts to cut costs and shore up its finances.

Nov. 12, 2024: Spirit Airlines said is in constructive discussion with its creditors and continues to explore strategic alternatives to improve liquidity, amid reports of merger talks with Frontier breaking down.

Nov. 18, 2024: Spirit Airlines filed for bankruptcy protection, after struggling with a long run of quarterly losses, failed merger attempts and looming debt maturities.