Kalshi and Polymarket volumes questioned; in Robinhood's Fed-cuts market, 75% of open contracts sit on 1% long shots

Trading volumes on some Kalshi and Polymarket products are drawing questions from industry observers who worry the numbers may be inflated, CNBC reported on Wednesday. On Polymarket's international exchange, which U.S. regulators do not oversee, contracts with low odds of happening have drawn more activity than likely ones. CNBC gave the example of the 2026 World Cup: $158 million traded on Egypt winning, an outcome that never went above 0.5%, against $152 million on Spain, which won. Both companies told CNBC that wash trading does not happen on their platforms, and Polymarket attributed the pattern to active traders correcting mispriced contracts.

That matters beyond the platforms themselves. CNBC noted that Polymarket is raising money at a valuation above $20 billion and Kalshi is reportedly in talks at $40 billion, both have pointed to volume growth as evidence of demand, and both are reportedly exploring public listings as soon as next year.

What our own data shows

We collect the public event pages of Robinhood's prediction markets each morning, including open interest, the number of contracts outstanding. Volume is missing or zero for most contracts in that feed, so we cannot test volume properly. We can check where open positions sit. As of 7:30 a.m. Eastern on Wednesday:

The rate-cuts market shows it most clearly. "Exactly 0 cuts" is priced at 95% and has 1,135,641 open contracts. "Exactly 15 cuts" is priced at 1% and has 316,252. "Exactly 14 cuts" and "Exactly 17 cuts" each have more than 300,000 open contracts. Prices here are rounded to the nearest percent, so a 0 means less than half of one percent.

The October Fed market has the same pattern in miniature. A 25 basis point cut, priced at 1%, has 364,450 open contracts. A 25 basis point hike, priced at 41%, has 217,465.

Why contract counts mislead

This is not proof of wash trading, and we are not suggesting it is. Every yes-or-no contract has two sides whose prices add up to 100%. Counting contracts treats a 1% long shot the same as a 95% favorite, even though a dollar buys about 95 times as many of the long-shot contracts on the yes side. Whoever holds the no side of that long shot is paying close to full price for a small return if nothing happens. Both behaviors inflate contract counts on unlikely outcomes without anyone faking a trade.

So headline "contracts traded" or "open interest" figures say little on their own about how much money is actually at risk or how much real disagreement there is. For anyone judging these platforms' growth, or looking at an eventual listing, the better question is dollar value by price bucket, and neither company's headline volume figures break that out.

The signal in the rate-cuts market is the price, not the contract count: 95% on no cuts this year, and in the separate October decision market, 59% on holding rates and 41% on a 25 basis point hike, as of Wednesday morning. We covered the regulatory side of the Kalshi volume story here.

Sources: CNBC; Robinhood prediction markets public event pages, collected Sept. 30, 2026, 7:30 a.m. ET. Open-interest shares are Chronicle calculations. Prediction-market prices are what traders are paying, not forecasts. This is market information, not investment advice.