The Ontario Line is a 15.6-kilometre, 15-station rapid transit line currently under construction in Toronto. It was originally planned for a 2027 opening date, which has since been pushed back to 2031. In February 2026, Premier Doug Ford suggested an opening date in the "early 2030s".

This market will resolve to the first date on which the public can ride the full 15.6 km length of the planned line from Exhibition Place to Don Valley Station at Eglinton and Don Mills. If the route is adjusted before project completion, this market will resolve to the first date on which the public can ride the "full length" of the line, based on the creator's best judgment. If the project is split into phases and some stations are opened earlier than others, partial opening does not count as "fully built," and the market will not resolve until the full line is open to the public.