Polymarket investigated dozens of midterm bets, NPR reports

Updated 31 October 2026: This report now includes the Warren–Curtis letter, dated 28 October and publicly announced on 29 October.

Senators seek answers by Election Day

Senators Elizabeth Warren and John Curtis have asked Kalshi and Polymarket to explain how they prevent improper election-related trading. Their 28 October letter, announced on 29 October, requests written responses by 3 November.

The questions cover restrictions on candidates and campaign insiders, confidential information, wash trading and independent evaluations of surveillance systems. The senators also seek counts of suspected cases identified since 1 January, distinguishing activity stopped before trading from cases detected afterwards and asking how many were referred to authorities.

The letter raises concerns and requests evidence. It is not a finding that either company violated the law. Its Polymarket addressee is Blockratize, Inc. doing business as Polymarket; the correspondence should not be treated as an inquiry solely into Polymarket US.

Polymarket’s earlier investigation disclosure

Polymarket has investigated dozens of midterm-related bets, its head of global intelligence and investigations, Shana Bautista, told NPR in a report published October 27.

NPR separately reported that at least two investigations had been referred to the Commodity Futures Trading Commission, citing an unnamed person familiar with the probes. The referral claim was not attributed to Bautista.

What Polymarket disclosed

Bautista, a former FBI official, said a 16-person team and an election-surveillance system monitor trading ahead of the November 3 midterms. Its inputs include public social-media information, Federal Election Commission records, banking partners and statistical models.

She described hundreds of daily alerts but did not disclose detection thresholds, citing system security. Alerts, investigations and referrals are different stages of a review; none alone establishes misconduct.

Her team covers both Polymarket’s US-regulated exchange and its international platform. NPR’s report does not identify the traders involved in the referred cases or establish their outcomes.

Separate from the platform-access inquiry

This disclosure concerns possible misconduct by market participants. Prediction Frontier’s separate report on renewed scrutiny of Polymarket’s 2022 settlement concerns the operator’s own compliance.

Prediction Frontier’s midterms market brief examines trading activity and concentration. Those measures describe how a market trades; identifying insider dealing requires evidence about the information or conduct behind particular transactions.