Check out the companies making headlines in midday trading.

Delta, United, American Airlines — Airline stocks fell in tandem as concerns about a rebound in Covid-19 cases intensified.  Shares of Delta and American Airlines all lost more than 3%. United declined over 4%. Aircraft manufacturer Boeing‘s stock also fell about 5%. Covid cases have ticked up in the U.S. this month with the delta variant spreading among the unvaccinated.

Carnival, Norwegian Cruise Line — Shares of cruise line operators were among the biggest laggards amid Monday’s broad sell-off. Carnival and Norwegian Cruise Line dropped about more than 4% each, while Royal Caribbean fell over 3%. The decline came as the U.S. is averaging nearly 30,000 new cases a day in the last seven days ending Friday, up from a seven-day average of around 11,000 cases a day a month ago, according to CDC data.

Diamondback Energy, Devon Energy, Marathon Oil — Shares of oil companies sunk amid falling U.S. oil prices as OPEC and its allies agreed to raise output. West Texas Intermediate crude futures fell below the key $70 level Monday for the first time in more than a month. Diamondback Energy slid 7.8%, and Marathon Oil fell 6%. Devon Energy erased 5%. Chevron shed more than 3%, while Exxon Mobil declined over 4%.

JPMorgan, Morgan Stanley, Goldman Sachs — Bank stocks took a hit Monday as bond yields plummeted, crimping their profitability prospects. JPMorgan, Morgan Stanley, Goldman Sachs and Wells Fargo all slid over 3%. Bank of America dropped more than 2%, and Citi fell over 3%.

Peloton, Chewy, DoorDash — Shares of companies that benefited from consumers staying at home amid the pandemic saw a boost on Monday as concerns of the spreading delta Covid variant heightened. Exercise company Peloton and pet supplies online retailer Chewy added more than 6% each. Food delivery service DoorDash rose more than 4%. Grocery store companies Albertsons climbed 0.9%, while Kroger gained more than 1%.

Tractor Supply – Tractor Supply’s stock fell about 6% despite a better-than-expected second-quarter earnings report. The farm equipment and services company posted quarterly earnings of $3.19 per share on revenues of $3.6 billion, beating analysts’ earnings estimate of $2.96 per share on revenues of $3.46 billion.

Zoom Video — Shares of the video conferencing company dipped over 4% on Monday after accounting that it’s buying Five9, a provider of cloud contact center software, in an all-stock transaction valuing the company at $14.7 billion. The deal marks Zoom’s first billion-dollar acquisition.

Moderna – Moderna shares added more than 7%, continuing the stock’s climb after news last week that the pharmaceutical company would join the S&P 500 on Wednesday, July 21. Moderna will replace Alexion Pharmaceuticals, which is being acquired by AstraZeneca.

— CNBC’s Yun Li, Maggie Fitzgerald and Tanaya Macheel contributed reporting