(Reuters) - No-frills air travel pioneer Spirit Airlines ( SAVE ) filed for bankruptcy protection on Monday, after struggling with a long run of quarterly losses, 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 ( JBLU ) 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 ( SAVE ), along with budget carrier

peer Frontier Group Holdings ( ULCC ), 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 ( JBLU ) 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 ( JBLU ) offer, saying

it had a low likelihood of winning approval

from government regulators on antitrust risks.

May 16, 2022 JetBlue ( JBLU ) launched a hostile all-cash takeover

bid for Spirit Airlines ( SAVE ), two weeks after the

rejection of its earlier offer.

May 19, 2022 Spirit urged shareholders to reject a hostile

bid by JetBlue ( JBLU ), 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 ( JBLU ) citing antitrust

concerns, weeks after it raised offer with

higher break-up fee and new ticking fee,

amounting to a $3.8 billion bid.

July 27, 2022 Spirit Airlines ( SAVE ) 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 ( JBLU ).

JetBlue ( JBLU ) prevailed in the months'

July 28, 2022 long bidding war for Spirit Airlines ( SAVE ) 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 ( JBLU ) 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 anticompetitive 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 ( JBLU )

remained intact, with the two companies

appealing the federal judge's ruling.

March 4, 2024 JetBlue ( JBLU ) 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 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 ( SAVE ) 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 ( SAVE ) 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 ( SAVE ) filed for bankruptcy

protection, after struggling with a long run

of quarterly losses, failed merger attempts

and looming debt maturities.

(Reporting by Aatreyee Dasgupta in Bengaluru; Editing by Anil D'Silva)