Jennifer Sey had been waiting for an athlete like Sophie Cunningham.

Sey, the founder of XX-XY Athletics, a sportswear startup that openly calls transgender people’s identity a “lie,” has spent the last two and a half years stoking the flames of the national panic over trans athletes. A former marketing executive at Levi’s, Sey was now running a company that produced viral video ads showing young female athletes pleading for others to defend them against a looming transgender threat. Meanwhile, Sey and the brand offered cash rewards to athletes who boycotted matches against trans athletes or spoke out against them—incidents that fueled right-wing outrage cycles. And it gave endorsement deals to students willing to denounce trans teammates or competitors. [...]