As U.S. airline shares fell across the board on Thursday, one major airline announced its commitment to investing billions into San Francisco International Airport.

United Airlines announced it will increase its flights out of SFO by 20% this summer. The airline will offer about 300 daily flights, which United claims is more than any other airline in the Bay Area.

In winter, United will add flights from SFO to Bangkok, Thailand, Ho Chi Minh City in Vietnam and Adelaide, Australia. The airline will also add a second flight between SFO and Manila, Philippines.

Kirby also emphasized his commitment to continue on with a $2.6 billion construction project at SFO. Set for completion in 2029, the project would modernize and expand Terminal 3.

United said it plans to hire 1,200 Bay Area employees this year. Last year, United said hired more than 1,600 people across the region.

"United is one of the biggest employers in the Bay Area, and the biggest employer at SFO," SFO Airport Director Mike Nakornkhet said on Thursday.

United's investments come at a time when most U.S. airlines have trimmed flights to protect margins on slow demand and avoid lowering fares, according to Reuters. 

United Airlines stock (UAL) closed 15.61% lower on Thursday at $60.23, but CEO Scott Kirby said he believes his company can weather any economic storm.

"Even if there's this economic downturn in the short term, those things happen. But (the near-term future and the long-term future) are both bright for us here at United," Kirby said on Thursday. "The stock market has a lot of emotion, and fear tends to dominate in the short term. I'm looking more at the facts.

Kirby said United is "increasingly winning brand-loyal market share" and set to have its most-profitable first quarter since the COVID-19 pandemic halted air travel.