Shayne Coplan has reportedly taken his fight with Tarek Mansour far beyond the business rivalry between Polymarket and Kalshi. The Polymarket chief has been accused of calling Kalshi a copycat, using the nickname Little Tarek around New York City offices and pushing an unconfirmed rumor that Mansour and Luana Lopes Lara once dated and that she cheated on him.
The reported personal campaign lands because Mansour is not a distant rival. He leads Kalshi, the company that has reportedly grown bigger than Polymarket, and Coplan’s comments now read less like trash talk than a public attempt to wound a competitor by name. At the center of it is a rumor that has spread far enough to become part of the feud itself, even though Kalshi’s spokeswoman, Elisabeth Diana, has denied it outright and said Lopes Lara has never cheated on anyone.
Coplan’s interest in the rivalry has already been visible in public. Last November, he told 60 Minutes that Polymarket is the most accurate thing we have as mankind right now, a line that now sits awkwardly beside the newer allegations about gossip, insults and office chatter. The contrast matters because it shows the feud is not only about markets or accuracy; it is also about status, reputation and the kind of personal damage that can travel faster than any product launch.
The rumor has a specific hook. Sources told The Post that some people understood Mansour and Lopes Lara to be dating when they were students at the Massachusetts Institute of Technology, but neither Kalshi’s co-founders nor anyone else has publicly confirmed a relationship. Coplan, meanwhile, is said to have kept repeating the claim anyway and to have told colleagues that Lopes Lara cucked Mansour, language that makes the dispute feel less like business competition than a running office grudge.
There is another reason the story has stuck. Kalshi reportedly tipped off the feds ahead of the November 2024 FBI raid of Coplan’s apartment, when agents seized his electronic devices in a search tied to whether Polymarket was facilitating illegal gambling. Coplan was never arrested or charged after that seizure, but the sequence gives the feud a sharper edge: it is not only about who is beating whom in the market, but about who was willing to help bring in investigators first.
That is why the latest claims around Tarek Mansour matter now. They fold a corporate battle, a federal investigation and a personal rumor into one dispute that is still widening, with no sign of any legal or corporate follow-up that would settle it. For Mansour, the immediate problem is not just competition from Polymarket. It is that Coplan appears willing to keep turning a business fight into a public smear.
