For the purposes of this market, a "major candidate" is defined as any candidate who, at any point during the race, had a polling average of at least 10%. In previous years, according to realclearpolling.com, the candidates who would have met this criteria were:

2024: Donald Trump, Ron DeSantis, Nikki Haley

2020: Donald Trump

2016: Donald Trump, Ted Cruz, Ben Carson, John Kasich, Marco Rubio, Jeb Bush, Scott Walker, Carly Fiorina, Rand Paul

2012: Mitt Romney, Newt Gingrich, Rick Santorum, Rick Perry, Herman Cain, Ron Paul, Michele Bachmann

2008: John McCain, Rudy Giuliani, Mike Huckabee, Mitt Romney, Fred Thompson