Delta Air Lines, Inc. provides scheduled air transportation for passengers and cargo in the United States and internationally. The company operates through two segments, Airline and Refinery. Its domestic network centered on core hubs in Atlanta, Minneapolis-St. Paul, Detroit, and Salt Lake City, as well as coastal hub positions in Boston, Los Angeles, New York-LaGuardia, New York-JFK, and Seattle; and international network centered on hubs and market presence in Amsterdam, Bogota, Lima, Mexico City, London-Heathrow, Paris-Charles de Gaulle, Sao Paulo, Seoul-Incheon, and Tokyo. The company sells its tickets through various distribution channels, including delta.com and the Fly Delta app; acts as a reservations specialists; and operates online travel and traditional brick and mortar agencies. It also provides aircraft maintenance and engineering support, repair, and overhaul services; and vacation packages to third-party consumers. The company operates through a fleet of approximately 1,273 aircrafts. Delta Air Lines, Inc. was founded in 1924 and is based in Atlanta, Georgia.

Southwest Airlines Co. operates as a passenger airline company that provides scheduled air transportation services in the United States and near-international markets. As of December 31, 2023, the company operated a total fleet of 817 Boeing 737 aircraft; and served 121 destinations in 42 states, the District of Columbia, and the Commonwealth of Puerto Rico, as well as ten near-international countries, including Mexico, Jamaica, the Bahamas, Aruba, the Dominican Republic, Costa Rica, Belize, Cuba, the Cayman Islands, and Turks and Caicos. It also provides inflight entertainment and connectivity services on Wi-Fi enabled aircraft; and Rapid Rewards loyalty program that enables program members to earn points for dollars spent on Southwest base fares. In addition, the company offers a suite of digital platforms to support customers' travel needs, including websites and apps; and SWABIZ, an online booking tool. Further, it provides ancillary services, such as Southwest's EarlyBird Check-In, upgraded boarding, and transportation of pets and unaccompanied minors. Southwest Airlines Co. was incorporated in 1967 and is headquartered in Dallas, Texas.

American Airlines Group Inc., through its subsidiaries, operates as a network air carrier. The company provides scheduled air transportation services for passengers and cargo through its hubs in Charlotte, Chicago, Dallas/Fort Worth, Los Angeles, Miami, New York, Philadelphia, Phoenix, and Washington, D.C., as well as through partner gateways in London, Doha, Madrid, Seattle/Tacoma, Sydney, and Tokyo. It operates a mainline fleet of 965 aircraft. The company was formerly known as AMR Corporation and changed its name to American Airlines Group Inc. in December 2013. American Airlines Group Inc. was founded in 1926 and is headquartered in Fort Worth, Texas.

Alaska Air Group, Inc., through its subsidiaries, operates airlines. It operates through three segments: Mainline, Regional, and Horizon. The company offers scheduled air transportation services on Boeing jet aircraft for passengers and cargo in the United States, and in parts of Canada, Mexico, Costa Rica, Belize, Guatemala, and the Bahamas; and for passengers across a shorter distance network within the United States, Canada, and Mexico. Alaska Air Group, Inc. was founded in 1932 and is based in Seattle, Washington.

Allegiant Travel Company, a leisure travel company, provides travel services and products to residents of under-served cities in the United States. The company offers scheduled air transportation on limited-frequency, nonstop flights between under-served cities and leisure destinations. As of February 1, 2024, it operated a fleet of 126 Airbus A320 series aircraft. The company also provides air-related services and products in conjunction with air transportation, including baggage fees, advance seat assignments, travel protection products, priority boarding, a customer convenience fee, food and beverage purchases on board, and other air-related services, as well as use of its call center for purchases. In addition, it offers third party travel products, such as hotel rooms and ground transportation, such as rental cars and hotel shuttle products; and air transportation services through fixed fee agreements and charter service on a year-round and ad-hoc basis. Further, the company operates a golf course. Allegiant Travel Company was founded in 1997 and is based in Las Vegas, Nevada.

Sun Country Airlines Holdings, Inc., an air carrier company, operates scheduled passenger, air cargo, charter air transportation, and related services in the United States, Latin America, and internationally. It operates through two segments, Passenger and Cargo. The company also provides crew, maintenance, and insurance services through ad hoc, repeat, short-term, and long-term service contracts; and loyalty program rewards. As of December 31, 2023, its fleet consisted of 60 Boeing 737-NG aircraft, which includes 42 passenger fleet, 12 cargo, and 6 leased to unaffiliated airlines aircraft. The company serves leisure, and visiting friends and relatives passengers; charter and cargo customers; military branches; collegiate and professional sports teams; wholesale tour operators; schools; companies; and other individual entities through its website, call center, and travel agents. Sun Country Airlines Holdings, Inc. was founded in 1983 and is headquartered in Minneapolis, Minnesota.

Spirit Airlines, Inc. provides airline services. The company also offers hotels and rental cars services. It serves 93 destinations in 15 countries in the United States, Latin America, and the Caribbean. As of December 31, 2023, the company operated a fleet of 205 Airbus single-aisle aircraft. The company was formerly known as Clippert Trucking Company and changed its name to Spirit Airlines, Inc. in 1992. Spirit Airlines, Inc. was incorporated in 1964 and is headquartered in Miramar, Florida.

Mesa Air Group, Inc. operates as the holding company for Mesa Airlines, Inc. that provides regional air carrier scheduled passenger services. The company offers scheduled flight and cargo services. As of September 30, 2023, it operated a fleet of 80 aircraft with approximately 296 daily departures to 86 cities in the United States and Mexico. Mesa Air Group, Inc. was founded in 1982 and is headquartered in Phoenix, Arizona.