Disclaimer: I contribute work as a political advisor and don't participate in betting markets as a market participant.

Nevertheless, Polymarket is a very interesting marketplace of sentiments and information, and it can be a very strong leading indicator of huge price movements in "real" markets like the NYSE, in part because it directly measures one factor of sentiment, i.e. whatever the prediction is about. Market sentiment determines market prices on very large and deep markets, too.

In the run-up to the election, when Trump was running against Biden, a betting market was a leading predictor of NASDAQ (a very deep, very liquid index of stocks). I wrote up the findings here: https://medium.com/@rviragh/does-the-stock-market-react-posi...

This indicator was the best one anyone has ever shown for NASDAQ for any signal, period. The signal was so strong it trumped all other signals and variances of any kind. Traders trading with just this signal and no other signal of any kind could have made practically an unlimited amount of money as long as the signal was intact. (Basically, until Biden dropped out.)

I myself didn't place any bet due to my role as a political advisor at the time, but the size of the correlation is still the biggest and most surprising one I've ever seen.