Polymarket
KalshiIllinois's 8th District: Without Krishnamoorthi, the Market Still Prices a Democratic Hold
The Illinois 8th District odds 2026 board is the closest-priced House race in the state, and even so the market rests on the district's partisan record rather than on who holds the seat. Raja Krishnamoorthi, the Democrat who has represented the 8th, gave it up to run for the U.S. Senate, so Melissa Bean, a Democrat, and Jennifer Davis, a Republican, are contesting an open seat on November 3, 2026. The live board above carries Kalshi's and Polymarket's current prices for each party.
Why the Illinois 8th District Seat Is Open
The Clerk of the House member list, published October 1, 2026, records Krishnamoorthi, of Schaumburg, as the Democratic member for the 8th District. He ran in the March 17, 2026 Democratic primary for the U.S. Senate instead of for re-election and finished second there with 411,150 votes, so his name is not on the State Board of Elections' list of House candidates for November. Shaw Local described him on primary night as a five-term incumbent.
The Board's general-election list, as of October 16, 2026, shows exactly two candidates for the 8th: Melissa L. Bean for the Democrats and Jennifer Davis for the Republicans. No independent or third-party candidate is listed, so the seat is a straight two-party choice.
How Bean and Davis Won Their Primaries
Both nominations were contested on March 17, 2026, and both winners entered late. Shaw Local reported that Bean and Davis announced their campaigns in mid-September 2025, after both primaries were already under way.
Bean won the eight-way Democratic primary of March 17, 2026 with 22,279 votes, 31.59% of the party's total, ahead of Junaid Ahmed with 18,954, 26.88%. Dan Tully, Yasmeen Bankole, Kevin B. Morrison, Neil Khot, Sanjyot Dunung and Ryan Vetticad split the rest. That means more than two in three Democratic primary voters chose someone other than the nominee. Shaw Local describes Bean as a former member of the U.S. House.
Davis won the four-way Republican primary held March 17, 2026 with 14,635 votes, 51.45%, against Mark Rice with 11,437, 40.21%, which made her the only nominee of either party in the district to win a majority of her own primary. Rice was the Republican nominee for this seat in 2024. Shaw Local describes Davis as the co-founder and former chief executive of an international software company and the author of a book, "Living Exponentially."
The two primaries were very different in size. The Board's totals show 70,518 votes cast across the eight Democratic candidates and 28,446 across the four Republicans. Bean's 22,279 votes alone were more than Davis's 14,635, which is a measure of primary turnout rather than a forecast, but it points the same way as the general-election record.
Why the Illinois 8th District Price Leans Democratic
What the price is saying is that the 8th has voted for Democratic House candidates by double digits in each of the last two elections, and that an open seat does not by itself erase that margin. The Clerk of the House's statistics for the November 5, 2024 election show Krishnamoorthi with 172,920 votes to 130,153 for Rice, a margin of 42,767 out of 303,073 cast. In 2022 the State Board of Elections' totals had Krishnamoorthi at 117,880 votes to 89,335 for Chris Dargis. Neither race was close enough for the incumbent's name to have been the deciding factor.
On October 16, 2026, Polymarket had the Democratic contract at 95%, the cheapest Yes on that side, against Kalshi's 96%. Polymarket's 5% was the cheapest Republican Yes, against Kalshi's 7%. That still makes the Democrats heavy favorites, but on that date it was the lowest price for the favorite on any of Illinois's seventeen House boards, which means traders see an open seat as the likeliest place in the state for a surprise even while they expect a hold.
The money traded on the board says the same thing in a different way. As of October 16, 2026 the board carried about $22K in lifetime volume on Polymarket, about $12K of it on the Republican contract against $10K on the Democratic one, and Kalshi had matched about 8,400 contracts, about 6,900 of them on the Republican side. More money has gone to the underdog side here than to the favorite, which is consistent with traders taking the upset scenario more seriously than on the state's safer boards.
The Case Against the Illinois 8th District Read
The strongest case against the read is that the double-digit margins belonged to Krishnamoorthi, not to the district. He had run and won here repeatedly; Bean is a nominee whom fewer than a third of Democratic primary voters chose, after a late entry into a crowded field. A reader who holds the counterread would point out that an open seat with a fractured primary is exactly the race in which a strong Republican nominee can outperform the district's past results.
Davis gives that view a candidate. She won her primary outright against the party's 2024 nominee, and Shaw Local's description of her as a technology company founder gives her a different profile from the nominee who lost here by 42,767 votes in 2024. The Republican contract's larger share of the trading on both venues shows that some traders are putting money behind this reading.
The price's answer is arithmetic. More than twenty thousand voters who backed the Democrat in 2024 would have to switch sides to erase a 42,767-vote margin, in a district where Democratic primary turnout ran more than twice the Republican figure in March. That is a large swing to expect from a change of candidates alone.
What Changes the Illinois 8th District Read
The read would be wrong if evidence emerges that the open seat has made the 8th competitive. The dated conditions to watch:
• Independent polling: Any public survey of the Bean and Davis race before November 3, 2026. A margin inside the poll's error would mean the price has not caught up.
• Fundraising: The candidates' next reports to the Federal Election Commission show whether Davis can match the Democratic nominee's money for an open seat.
• Ballot access: October 19, 2026 is the last day a vacancy in nomination can occur and be filled, so the two-name ballot is effectively final.
• Early and mail voting: Early voting at permanent sites starts October 19; election authorities must receive mail-ballot applications sent by mail by October 29.
• Counting: Mail ballots postmarked by November 3 and received within 14 days are counted through November 17, 2026, which matters only if the race is close on election night.
When the Illinois 8th District Market Resolves
Kalshi resolves its Democratic contract Yes if the House member sworn in for IL-08 for the term beginning in 2027 is a member of the Democratic Party, and the Republican contract on the same test; it lists an expected settlement of January 4, 2027, with accelerated determination allowed once a consensus of media organizations projects the winner. Polymarket resolves on the party of the candidate who wins the seat, as indicated by a consensus of credible reporting, and falls back on the official results reported by the Federal Election Commission if there is ambiguity. Election authorities canvass by November 24, 2026 and the State Board of Elections proclaims the results by December 4.
Related Illinois Markets
The seat opened because of the Senate race on the same ballot, priced on the Illinois Senate odds page; the governor's race is on the Illinois governor odds page. The other House boards with pages of their own are the Illinois 2nd District odds, another seat vacated for the Senate primary, the Illinois 4th District odds, the Illinois 11th District odds and the Illinois 17th District odds. The Illinois elections page lists every race on the ballot.
