On May 17th, a trader bet ~$20 at 1c per share (implied 1% probability) on the wrong bucket for Mexico City temperature, and then bet again. That bucket won, and ~$50 turned into ~$5000.

On May 17th, Polymarket’s high temperature market for Miami was missing the winning bucket, and the ones around it.

Then, the May 17th market for Miami was “archived” — which is not what happens to markets that are resolved normally — along with the money that people had bet on it. Other markets followed (or preceded; its hard to find a clear timeline).

There was no official response from Polymarket about what had happened, and speculation was confined to the comments, X, and Reddit.

Someone speculated that it was an exploit, pointing to the Mexico City trader’s wallet (though that person might have just noticed something was weird, or gotten lucky):

Rumors surfaced of an Oracle bug:

Eventually, all US and international temperature markets disappeared, not just for May 17th, retroactively, but also for May 18th to May 22nd:

The only acknowledgement from Polymarket so far seems to be this tweet from @kea1on:

The Polymarket status page shows no notices for May 16th, 17th, or 18th:

Polymarket - Status

Polymarket Status

Polymarket