Shares of United Continental fell by 2 percent Tuesday as outrage over Dr. David Dao of Kentucky being dragged off an overbooked flight finally caught up to the stock. The shares were among the worst performers in the S&P 500.

The airline's stock, however, climbed nearly 1 percent Monday, not reacting much initially to the internet's response.

Videos of the incident went viral on social media and prompted CEO Oscar Munoz to apologize for having to "re-accommodate" customers after a two-hour delay. The confrontation happened on a United Express flight operated by Republic Airways.

Munoz issued a second apology Tuesday afternoon in which he said the company "will fix this." "It's never too late to do the right thing. I have committed to our customers and our employees that we are going to fix what's broken so this never happens again," he said. The company's stock traded off the lows of the day amid the second Munoz apology.

Overnight, though, even more graphic videos showing Dao being dragged off the flight, covered in blood, triggered further outrage on social media on China.

Although the doctor's identification as ethnic Chinese has not be confirmed, the top trending topic on Tuesday on microblog Weibo, China's take on Twitter, was #UnitedAirlinesforcespassengeroffplane.

"This went to the next level when the CEO and the [United] executives began to respond," said Andy Swan of LikeFolio, which monitors social media for financial applications. "They threw gasoline on a fire."