**Proposition 134, a citizen-initiated statute on Colorado’s November 3, 2026 ballot, requires K-12 and collegiate athletic teams to be designated male, female, or co-ed based on biological sex as defined by reproductive anatomy, restricting participation accordingly.** The measure, advanced by Protect Kids Colorado after signature collection, addresses existing state policies allowing participation consistent with gender identity and would take effect January 1, 2027. Recent voter guides and campaign activity highlight debates over fairness in girls’ sports, enforcement methods, and potential impacts on school policies. National trends, including federal funding pressures on districts with inclusive rules, have reinforced momentum for sex-based categories. Trader pricing at 68.5% for passage reflects this ballot positioning and patterns seen in comparable state measures, while acknowledging the final outcome depends on turnout and undecided voters in the remaining weeks.