With air-travel demand improving in the United States (particularly for leisure), United Airlines UAL raised its total unit revenue guidance for the second quarter of 2021. In fact, driven by the uptick in air-travel demand, Hawaiian Holdings HA too provided an upbeat outlook for second-quarter 2021 revenues.Further, Allegiant Travel Company ALGT announced its intention to add six routes later this year to its network in a bid to meet the anticipated demand swell during summer. JetBlue Airways JBLU also hit the news headlines, courtesy of its decision to appoint a new chief people officer.Recap of the Past Week’s Most Important Stories1. In a SEC filing, United Airlines’ management stated that as of May 25, 2021, “consolidated yields on tickets issued since the beginning of May 2021 for travel in the second quarter 2021 have reached levels similar to 2019, with domestic leisure yields exceeding 2019 levels for the same time period.” Consequently, the company now expects Total Revenue per Available Seat Mile or TRASM to decline approximately 12% in the second quarter of 2021 from the reading recorded for the same period in 2019. This is an improvement from the carrier’s previous guidance of a decrease of around 20%. Due to better yield performance, United Airlines, currently carrying a Zacks Rank #3 (Hold), estimates its adjusted EBITDA margin for the second quarter to be around (11%), higher than the previous expectation of about (20%).Southwest Airlines LUV had also issued a bullish update for second-quarter cash flow owing to the uptick in air-travel demand as elucidated in the previous week’s write-up.You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.2. Citing strong demand for air travel in its markets across North America, Hawaiian Holdings expects second-quarter revenues to plunge in the 42-46% range from the second-quarter 2019 actuals. The fresh guidance improved from the previous forecast of a 45-50% decline. Backed by a stronger revenue scenario, the company now predicts adjusted EBITDAAR (Earnings before interest, taxes, depreciation, amortization and restructuring or rent costs) between a negative $40 million and a negative $10 million compared with its prior anticipation of a negative $70 million and a negative $20 million.3. Allegiant aims to start six nonstop flight services in the summer of 2021, offering customers connectivity to premier destinations in Florida and the west. The carrier’s new menu includes two routes to the Phoenix Sky Harbor International Airport (PHX), which Allegiant will serve for the first time. As for Allegiant’s expansion to PHX, its first flight operations will begin in October with nonstop services to both Provo (starting Oct 8) and Stockton (effective Oct 15). Moreover, Aug 19 onward, the carrier will initiate operating a new nonstop route connecting the Phoenix-Mesa Gateway Airport with Pittsburgh, PA.4. Beginning the current month, Laurie Villa will be JetBlue’s chief people officer. She will be replacing the long-serving Mike Elliott, who will step down this August after being associated with the Long Island City, NY-based low-cost carrier since 2010. Notably, Villa is a veteran, having assumed various leadership roles for over two decades now. Of late, she was associated with another low-cost carrier Spirit Airlines SAVE in the capacity of a chief human resources officer for six-and-half years. At JetBlue, Villa will report directly to the CEO Robin Hayes.5. With sights set on meeting the anticipated demand surge during summer, Delta Air Lines DAL strengthened its long-standing interline partnership with the regional carrier Cape Air. Through this strategic move, the airline aims to provide its customers with access to more coastal destinations in the Northeast United States.PerformanceThe following table shows the price movement of the major airline players over the past week and during the last six months.Image Source: Zacks Investment ResearchThe table above shows that most airline stocks have traded in the green in the past week (although the gains were mostly tepid in nature), leading the NYSE ARCA Airline Index to gain 1.6% over the past week to $107.58. Over the course of the past six months, the NYSE ARCA Airline Index has appreciated 27.8%.What's Next in the Airline Space?Stay tuned for May traffic reports from the likes of Ryanair Holdings RYAAY.Time to Invest in Legal MarijuanaIf you’re looking for big gains, there couldn’t be a better time to get in on a young industry primed to skyrocket from $17.7 billion back in 2019 to an expected $73.6 billion by 2027.After a clean sweep of 6 election referendums in 5 states, pot is now legal in 36 states plus D.C. Federal legalization is expected soon and that could be a still greater bonanza for investors. Even before the latest wave of legalization, Zacks Investment Research has recommended pot stocks that have shot up as high as +285.9%You’re invited to check out Zacks’ Marijuana Moneymakers: An Investor’s Guide. It features a timely Watch List of pot stocks and ETFs with exceptional growth potential.Today, Download Marijuana Moneymakers FREE >> Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Southwest Airlines Co. (LUV): Free Stock Analysis Report JetBlue Airways Corporation (JBLU): Free Stock Analysis Report Ryanair Holdings PLC (RYAAY): Free Stock Analysis Report Delta Air Lines, Inc. (DAL): Free Stock Analysis Report United Airlines Holdings Inc (UAL): Free Stock Analysis Report Allegiant Travel Company (ALGT): Free Stock Analysis Report Spirit Airlines, Inc. (SAVE): Free Stock Analysis Report Hawaiian Holdings, Inc. (HA): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research