Longshot Bets Dominate Kalshi, Polymarket Despite Losses
A new Bloomberg analysis of Kalshi and Polymarket trading data found that bettors keep piling into longshot wagers that lose roughly 98% of the time, undercutting the platforms' pitch that prediction markets are neutral "truth machines."
Since early 2025, Bloomberg found that around half of all trading volume on Kalshi has involved one side of a bet chasing potential returns of at least 1,000%, the kind of odds more associated with a casino parlay than a forecasting tool.
On Polymarket, the pattern looks similar: longshot bets accounted for 52% of trading volume over the past 21 months. A Polymarket spokesperson pushed back on the framing somewhat, telling Bloomberg that longshot wagers represent only about 1% of the platform's total volume, though that still amounted to more than $600 million in September alone once Kalshi and Polymarket are combined. Kalshi declined to comment on the findings.
Losses Pile Up, and Fees Make It Worse
For bettors who take those odds, the math rarely works out. Bloomberg's analysis found that money staked on “yes” longshot positions lost an average of 15% on Kalshi and 27% on Polymarket, with platform fees of up to 7% adding to the losses.
Philip Newall, a former professional poker player now researching gambling behavior at the University of Bristol, told Bloomberg the bigger puzzle is why bettors can't recognize when they are on the losing side of these wagers.
Brian Cai, a former Meta Platforms employee who placed longshot bets alongside more measured ones, said he eventually realized how badly those positions were performing. The pattern fits a broader trend Bloomberg had already flagged: a previous report found that most Polymarket accounts lost money between January 2025 and April 2026.
The findings add to the scrutiny around prediction markets' sports contracts more broadly, which have also drawn legal challenges over whether they count as regulated gambling, like traditional sports betting.
Why Bettors Keep Chasing Longshots
Researchers who study gambling behaviour say the appeal is less about the underlying event and more about the rush of a big, unlikely payout. Newall's research background is in poker, where players similarly misjudge rare, high-value outcomes, and he argues prediction-market bettors show the same blind spot when a contract offers a shot at a ten-times or hundred-times return.
Cai's own experience, piling into longshot contracts alongside steadier bets before recognising the pattern in his own results, is the kind of behaviour Bloomberg's data suggests is common rather than rare across both platforms.
With Kalshi and Polymarket both expanding into new sports and political contracts, the volume of money flowing into these low-probability bets looks likely to keep growing even as the loss rates stay stubbornly one-sided.
Neither Kalshi nor Polymarket has announced plans to limit how longshot contracts are marketed or priced, leaving the behavioural pattern Bloomberg documented largely unaddressed for now.
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