Shares of United Airlines fell Tuesday after a passenger who appeared to be Asian was physically dragged off a flight on Sunday, prompting a backlash on social media in China and around the world.

United Airlines' decision to drag the passenger off a flight from Chicago to Louisville on Sunday attracted more than 130 million views on the Weibo platform by Tuesday afternoon.

The backlash in Asia is a problem for the company, as the continent is a key growth area for many U.S. carriers.

United operates more non-stop flights from the U.S. to more cities in China than any other airline. The company got about 14 per cent of its 2016 revenue from flying Pacific routes.

Shares in United Continental Holdings, the airline's parent company, closed down by more than one per cent in New York on Tuesday, after earlier having been as much as four per cent lower. At its lowest point, that was the equivalent of about $1 billion US worth of the company's market value.

Prior to this week's news, United Airlines shares had been climbing steadily this year, up 15 per cent after the company raised its flight capacity forecast for the first quarter. Last year, U.S. airlines saw a decline in unit revenue, a closely watched measure, due to higher capacity and lower fares.

State-run Chinese media fuelled the anger with reports that noted the unidentified victim was an "Asian passenger."

"Damn it! This airline must be boycotted!" said a posting from Liu Bing, a telecommunications company worker.

Late in the day on Tuesday, United's CEO Oscar Munoz put out a public statement apologizing for the incident. "My deepest apologies for what happened," he said. "Like you, I continue to be disturbed by what happened on this flight and I deeply apologize to the customer forcibly removed and to all the customers aboard. No one should ever be mistreated this way." 

Marketing professor Monica LaBarge says that from a public relations perspective, the incident is a disaster that keeps getting worse.

"It was just bad judgment on the part of the number of people," the assistant professor of marketing at the Smith School of Business at Queen's University in Kingston, Ont., said in an interview with CBC News on Tuesday. "The police, the United Airlines employees, and ... maybe procedures not being in place that should have been there."

Coming on the heels of other incidents — including one last month in which two teenage girls wearing leggings were barred from boarding a United Airlines flight because they did not meet a dress code for special pass travellers, and the case of musician Dave Carroll, who had a viral hit in 2009 when the airline broke his guitar — it's taking a toll on the company.

In an interview with CBC on Monday, Carroll said it seems like United hasn't learned from its mistakes.

"My experience was that they had a ways to go," he said. "And it seems like maybe they have a ways to go yet."

Marketing professor LaBarge agrees with that assessment, saying the company's snowballing problems add up to a public relations nightmare.

"All of these things compounded start to make you feel like maybe I don't want to fly United," LaBarge said.

"Maybe I want to fly somebody else."

With files from The Associated Press and Reuters