Any New Yorker wanting a steer on how things might have panned out in the city’s recent mayoral election could have done so without so much as glancing at a newspaper, turning on the TV or scrolling through social media. All they had to do was to look upwards — at one of several giant digital billboards that had suddenly popped up all over the city centre, featuring some pretty attention-grabbing numbers. 

“94% MAMDANI 6% CUOMO”, the billboards screamed, along with the phrase “OKAY Trade” and then a company name: Polymarket. 

What was this? Was it some kind of an advert for the Democratic candidate (and eventual winner) Zohran Mamdani, or for a company called Polymarket? Did it reflect polling numbers, betting odds or something else? Were they numbers to be trusted?