United Airlines’ stock dropped on opening Tuesday, as anger spread on social media over the violent removal of a passenger from a flight.

Shares of United Continental Holdings Inc., United Airlines’ parent company, were down around four per cent as of mid-day Tuesday, trading at US$68.65, down from a close above $71.50 the day before.

That erased some US$900 million (C$1.2 billion) from the company’s value in the space of several hours. The company's market value sat at US$21.6 billion, down from US$22.5 billion at Monday's close.

The company's stock price recovered a good part of its early losses Tuesday, though it still closed down 1.1 per cent for the day. That left its market value down around $250 million from the day before.

All three of United's major competitors enjoyed an upswing in their stock price, with American Airlines closing up 3.8 per cent, at US$43.93, Delta Air Lines up 0.7 per cent to US$45.29 and Southwest up 1.55 per cent to US$55.06.

Boycott in the works

An editorial in China’s state-run Global Times wondered whether “the victim’s Chinese ethnicity potentially made a difference.”

The topic page for the subject on Sina Weibo, China’s equivalent of Twitter, had been viewed by more than 350 million users within a day, the South China Morning Post reports, with numerous people vowing to boycott the airline.

United Continental Holdings CEO Oscar Munoz issued an apology Monday “for having to re-accommodate these customers,” in reference to four people who were asked to leave a flight from Chicago to Louisville, in order to make room for United employees.

One of those passengers refused to move, and was dragged off the plane by Chicago aviation department police, in an incident that was caught on video and has spread around the world.

One of the officers involved has been put on leave.