Researchers Identify Suspicious Activity on Kalshi and Polymarket Before Times/Siena Poll Release
Published . Updated .
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A trader placed well-timed bets on Polymarket and Kalshi in two Senate races. It was unclear if the person had access to inside information or simply made good trades.
Directly affected
- No company is named in this report.
Indirectly affected
- IAI iShares U.S. Broker-Dealers & Securities Exchanges ETF
iShares U.S. Broker-Dealers & Securities Exchanges ETF: it holds exchanges and brokers. Linked by “kalshi” (exchanges and trading) in this story.
- CME CME Group+4.0% 13d
CME Group (security and commodity brokers, dealers, exchanges and services): exchanges and brokers earn more when trading activity grows. Linked by “kalshi” (exchanges and trading) in this story.
- ICE Intercontinental Exchange+12.8% 30d
Intercontinental Exchange (security and commodity brokers, dealers, exchanges and services): exchanges and brokers earn more when trading activity grows. Linked by “kalshi” (exchanges and trading) in this story.
- CBOE Cboe Global Markets+30.0% 30d
Cboe Global Markets (security and commodity brokers, dealers, exchanges and services): exchanges and brokers earn more when trading activity grows. Linked by “kalshi” (exchanges and trading) in this story.
- NDAQ Nasdaq+14.2% 30d
Nasdaq (security and commodity brokers, dealers, exchanges and services): exchanges and brokers earn more when trading activity grows. Linked by “kalshi” (exchanges and trading) in this story.
Price reaction, T-5 to T+3
| Ticker | T-5 | T-3 | T-1 | T0 | T+1 | T+2 | T+3 |
|---|---|---|---|---|---|---|---|
| IAI | +1.09% | +4.45% | base | after close | after close | after close | after close |
| CME | +0.11% | +0.73% | base | after close | after close | after close | after close |
| ICE | -0.01% | +1.55% | base | after close | after close | after close | after close |
| CBOE | -0.97% | -2.19% | base | after close | after close | after close | after close |
| NDAQ | +1.47% | +2.45% | base | after close | after close | after close | after close |
Closing-price change versus T-1, the last close before the story. T0 to T+3 fill in after each market close. Prices: Alpaca IEX.
A trader placed well-timed bets on Polymarket and Kalshi in two Senate races. It was unclear if the person had access to inside information or simply made good trades.
Source: The New York Times
This story
| Company | When | Move | Status |
|---|---|---|---|
| CBOE | three days earlier | -2.19% | final price |
| CBOE | five days earlier | -0.97% | final price |
| CME | three days earlier | +0.73% | final price |
| CME | five days earlier | +0.11% | final price |
| IAI | three days earlier | +4.45% | final price |
| IAI | five days earlier | +1.09% | final price |
| ICE | three days earlier | +1.55% | final price |
| ICE | five days earlier | -0.01% | final price |
| NDAQ | three days earlier | +2.45% | final price |
| NDAQ | five days earlier | +1.47% | final price |
Trades by members of Congress and officials in the stocks in this story
- Donald J Trump, an executive branch official, bought Cme Group (CME), worth $15,001 - $50,000 on 17 Aug 2026. That is 82 days before publication. Filed 8 Oct 2026. View the filing.
- Donald J Trump, an executive branch official, sold Cme Group (CME), worth $1,001 - $15,000 on 10 Aug 2026. That is 89 days before publication. Filed 8 Oct 2026. View the filing.
- Rep. April McClain Delaney sold Nasdaq (NDAQ) (held by a dependent child), worth $100,001 - $250,000 on 25 Aug 2026. That is 74 days before publication. Filed 9 Sep 2026. View the filing.
Public disclosure filings, not a recommendation. The filing link is the source document. News use of these reports still sits under 5 U.S.C. § 13107(c).
This story
12 out of 100
“Researchers Identify Suspicious Activity on Kalshi and Polymarket Before Times/Siena Poll Release” scores 12 out of 100. The score uses 1 sources.