A site called Contrary Research has a deep dive on prediction markets. They are similar to sports betting and options trading mathematically, but different in terms of legal and regulatory treatment (which is constantly litigated and evolving). There are concerns about insider trading. Despite all this, I like them just because they give us some more data points to look at. On political events, sometimes they echo polls and sometimes they tell a different story. On geopolitical events, they provide a somewhat objective, independent data point that might help us spot bullshit in the narratives we are being offered by the media.

Anyway, Polymarket and Kalshi are the big ones. There are others, and there is a blurring of the lines between sports books and prediction markets, which both starting to overlap each other. I was curious if there was an aggregation site for multiple prediction markets, and a popular one is Election Betting Odds. They are pretty true to their name and don’t cover everything on the prediction markets. At the moment, they show J.D. Vance and Marco Rubio leading Gavin Newsom for U.S. President in 2028. They show Democrats with an 80% chance of taking the House in November but the Republicans with a 56% change of continuing their majority in the Senate. Now, prediction markets are not always even consistent internally. If you go to Polymarket itself, they match that 56% chance of Republicans controlling the Senate, but another contract shows a 44% chance of a Democratic sweep of both levels of Congress (and a 41% chance of a Democratic House, Republican Senate. I’m having trouble wrapping my head around the probabilities here – are these things in fact inconsistent?)

Here is CBS News telling me “Senior defense officials looking at Cuba military options“. Well, today Polymarket thinks there is a 14% chance that the U.S. will invade Cuba in 2026 and a 31% chance of U.S. military action against Cuba by December 31, 2026. Well, I guess military action could fall short of an invasion so these two markets are not necessarily inconsistent.