Michael Saylor‘s Strategy (NASDAQ:MSTR) finally sold Bitcoin (CRYPTO: BTC) last week, but the disclosure timing and confusing Polymarket rules may have cost one trader $500,000.

The contract asking whether Strategy would sell any Bitcoin by May 31 drew roughly $54 million in total trading volume and sat around 80 cents on “Yes” heading into resolution. Trading volume has since climbed to roughly $143 million.

Strategy revealed in a June 1 Form 8-K filing that it had sold 32 BTC for roughly $2.5 million between May 26 and May 31. The sale itself landed inside the deadline. The disclosure did not.

Where UMA Comes In

A “No” resolution was proposed via UMA’s optimistic oracle, and Polymarket added a bulletin on the market page telling voters that no information from MSTR, on-chain data or credible reporting had confirmed a sale within the market’s timeframe, and that confirmation arriving outside the window did not qualify.

“Yes” shares collapsed from around 80 cents to less than a penny.

The June 30 and December 31 iterations of the same “Strategy sells Bitcoin” market resolved to “Yes” without dispute, triggered by the same June 1 filing.

Polymarket is arguing that the identical sale is valid for one contract but invalid for another, based on when the paperwork cleared.

The May 31 resolution has been disputed twice and is now heading to a vote by holders of UMA tokens, the oracle that settles contested Polymarket contracts.

The $500,000 Loss

A trader posting under the handle willo2 said on X he is out roughly $500,000 on the contract, and argued Polymarket rewrote the rules after the fact.

The original market language listed on-chain data, disclosures and credible reporting as resolution sources, without specifying confirmation had to land before the deadline.

“Under no circumstances should they be able to change the rules like this,” willo2 posted: “I was just scammed.”

A Wider Resolution Problem

Similar disputes have hit Polymarket before. A $242 million Zelenskyy-suit market settled “No” despite widespread media coverage of the outfit, and a $170 million US-Iran ceasefire market saw multiple rounds of disputed resolutions.

A May Wall Street Journal investigation found more than 60% of active UMA voters could be linked to Polymarket accounts, and roughly one in five disputed markets had at least one voter holding a position in the contract they were ruling on.

By contrast, Kalshi operates as a CFTC-registered exchange where disputes are handled internally, and ForecastEx settles event contracts under a similar regulated framework. Neither structure allows the kind of retroactive bulletin posted on the Strategy market.

Polymarket has logged more than 1,150 disputed markets as of mid-May, already past its full-year 2025 total.

Polymarket did not immediately respond to a request for comment.

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