President Trump signed an executive order Wednesday afternoon barring biological men who identify as transgender from competing in women’s sports. The tide is turning politically, legally, and in terms of public opinion on this issue, but will America’s largest athletic companies come on board?

This is Mr. Trump’s fifth executive order on transgender issues since entering the White House two weeks ago. Trump promised repeatedly on the campaign trail to “keep men out of women’s sports” to great applause.

“This commonsense action from President Trump ends the disgusting betrayal of women and girls by the previous administration, who for years, catered to radical activists who wanted biological males to be treated as women in workplace showers, competitive sports, prisons, and even rape shelters,” Trump press secretary, Karoline Leavitt, said Wednesday. “Gender ideology insanity is over.”

Protecting women’s sports has become a major culture war — and partisan — battle in the last few years. The Biden administration pushed policies — including its Title IX rewrite that a federal court struck down last month — to allow athletes to compete on sports teams that align with their gender identity, as opposed to biological sex.

President Biden also supported transgender medical care for minors and transgender access to women’s private spaces like bathrooms and prisons. Mr. Trump reversed these policies by executive order in his first days in office.

Yet despite nearly 70 percent of Americans thinking athletes should only compete on teams that match their biological sex, the largest sportswear and sports-related companies have yet to take this stance. Nike, Adidas, Gatorade, and Dick’s Sporting Goods are major financial sponsors of Athlete Ally, an organization that advocates for transgender competition in sports.

Nike’s website pushes “belonging and visibility in sport.” It says that, “Sport is better when all athletes are free to play as themselves.” The company has also sponsored transgender athletes.

Founder of XX-XY Athletics, Jennifer Sey — whose company’s mission is to protect women’s sports — posted to X on Tuesday an ad for her athleticwear company that calls out Nike specifically on its refusal to take a stand against biological men competing against women. Ms. Sey attended the executive order signing at the White House.

“Dear Nike, why won’t you stand up for me?” school-age girls ask in the XX-XY Athletics video advertisement. “You say you’re for social justice and progress, so why do you allow men’s rights to come before ours?”

Billionaire hedge fund manager, Bill Ackman, responded to Ms. Sey on X, saying that he will meet with Nike’s chief executive Elliott Hill on Thursday to “discuss this” with him. Mr. Ackman tells the New York Sun for Nike to back XX-XY Athletics’ campaign would be “good for America and good for business.”

Nike did not immediately return the New York Sun’s request for comment.

“Our hearts break for the trans youth who will no longer be able to know the joy of playing sports as their full and authentic selves,” Athlete Ally said in a statement. “We will continue to work with sporting bodies to expand access to the lifesaving power of sports whenever and wherever possible.”

More than half the states have already passed laws banning transgender participation in women’s sports. A senior legal adviser with Independent Women’s Forum, Beth Parlato, tells the Sun her organization is working to pass these bills and ones to strictly define sex based on biological reality in the states. The Georgia legislature is currently debating a transgender athlete ban.

Independent Women’s Forum is the leading conservative women’s rights group that is working on this issue. NCAA swimmer Riley Gaines works with the group. Ms. Parlato says with Biden’s Title IX rewrite struck down and Mr. Trump’s executive order defining men and women based on biological sex, “No national sports bill is needed.” The executive order signed by Trump today is a campaign promise fulfilled.