A Fox News host has apologised to a student who survived a Florida high school shooting that claimed 17 lives after accusing him of whining.
Several firms have answered David Hogg's call for a boycott of Laura Ingraham's show after she taunted him.
In an interview this week, the 17-year-old activist said four universities had rejected his applications.
The teenager has been a target of online abuse since the 14 February shooting in Parkland.
Ms Ingraham tweeted about him on Wednesday: "David Hogg Rejected By Four Colleges To Which He Applied and whines about it."
David, who gave a speech at last weekend's March for Our Lives gun-control protest, later tweeted: "Soooo @IngrahamAngle what are your biggest advertisers ... Asking for a friend. #BoycottIngramAdverts".
He later posted the names of 12 companies, encouraging his 611,000 Twitter followers to contact them.
One of the firms, Nutrish, replied to his tweet, pledging to remove its commercials from Ms Ingraham's programme.
Wayfair, a homeware retailer, and TripAdvisor, a travel website, also said they were pulling ads from the Fox show.
A TripAdvisor spokesperson said in a statement that Ms Ingraham's comments "cross the line of decency".
Wayfair said "the decision of an adult to personally criticise a high school student who has lost his classmates in an unspeakable tragedy is not consistent with our values".
Nestle, the world's largest packaged food company, online streaming service Hulu, and travel website Expedia also said they planned to pull ads from the show.
On Thursday, the Fox presenter struck a conciliatory tone, praising David's grades.
We are in the process of removing our ads from Laura Ingraham’s program.— Nutrish (@Nutrish) March 29, 2018
"On reflection, in the spirit of Holy Week, I apologize for any upset or hurt my tweet caused him or any of the brave victims of Parkland," she said.
Ms Ingraham also invited him to appear on her show "for a productive discussion", saying she had previously remarked how "poised he was given the tragedy".
Her tweet accusing him of being a whiner stemmed from an interview the teenager did with TMZ on Tuesday.
David told the celebrity gossip website he had been turned away from four colleges in the University of California system.
Any student should be proud of a 4.2 GPA —incl. @DavidHogg111. On reflection, in the spirit of Holy Week, I apologize for any upset or hurt my tweet caused him or any of the brave victims of Parkland. For the record, I believe my show was the first to feature David...(1/2)— Laura Ingraham (@IngrahamAngle) March 29, 2018
"It's been kind of annoying having to deal with that and everything else that's been going on but at this point, you know, we're changing the world," he said.
"I think there's a lot of amazing people that don't get to college not only that do things like I do, but because their voices just aren't heard in the tsunami of people that apply every year for college in such an economic impacted school system which we have here in America where people have to go into massive amounts of debt just to go to college and get an education."
He also said that he has a 4.2 grade-point average (GPA) and scored a 1270 on the SAT, a key college placement exam. Both scores are considered above average.
Harvey Levin, who conducted the interview for TMZ, had tweeted to Ms Ingraham that "David was not whining".
"He was not feeling sorry for himself in the slightest... Did you watch the video???" he posted.
How low are your ratings @IngrahamAngle that you have to start attacking my brother’s grades to get attention? If you ask me, he is more articulate than you and has far better character. Man, that’s real low even for you. Coming from a 14 year old, please grow up. #NeverAgain https://t.co/CgUVeGRfxP— Lauren Hogg (@lauren_hoggs) March 28, 2018
On Twitter, several other users defended the teenager.
"Are you really picking on a teenager who just watched his classmates die in pools of their blood less than two months ago?" one user wrote.
David's 14-year-old sister, who was also at Marjory Stoneman Douglas High School when gunshots rang out, also defended her brother.
"How low are your ratings @IngrahamAngle that you have to start attacking my brother's grades to get attention?" wrote Lauren Hogg.
"If you ask me, he is more articulate than you and has far better character. Man, that's real low even for you. Coming from a 14 year old, please grow up."
She asked First Lady Melania Trump, who has previously spoken out about online bullying, if she had any comment about her brother "literally getting cyberbullied".
Meanwhile, the son of right-wing provocateur Alex Jones, the host of InfoWars, has challenged David Hogg to a debate.
Also on Thursday, accused gunman Nikolas Cruz's brother, Zachary, was sentenced to six months probation for trespassing at the school where his brother admitted to killing 17 people in February.