Traders Defying US Ban Embrace Polymarket With Election Bets

On the top floor of a luxe hotel outside the Republican National Convention, amid a coterie of neatly coiffed GOP operatives in tailored suits, one person stood out in his dark T-shirt and a mop of curly hair.

That was Polymarket’s Shayne Coplan. The 26-year-old college dropout was introducing himself as the force behind the crypto-betting platform, which takes wagers on everything from election winners to whether the US will confirm the existence of aliens. At one point, Coplan’s schmoozing got him a seat next to Donald Trump Jr.

President Joe Biden’s withdrawal from the US race, the ...