At 3:28:11 p.m. Eastern on Friday, September 4, 2026, seven fills hit the Kansas Senate winner market on Kalshi in the same second, and every one of them bought Adam Hamilton. Together they took 78,069 contracts at 17¢ and 18¢, which works out to $13,784 of outlay that pays $78,069 if the Democrat is sworn in next January. Fifty-three seconds later another 29,952 contracts sold Roger Marshall at 83¢. Then the market did the thing that makes this page worth writing: close to nothing. Hamilton closed the session at 18¢, the same number he opened at, and Marshall closed at 83¢. The busiest session in the five and a half weeks of daily candles we pulled, roughly a fifth of everything this market has traded since it listed in December 2024, ended with Hamilton exactly where he started and Marshall a cent lower.
One afternoon holds the whole Kansas story. Since the August 4 primary the price has already done its arguing, running Hamilton from 16¢ to 23¢ and back to 18¢. What changed this week is not the number but the size of the money willing to sit on either side of it. What the tape rewards now is reading who is putting real money on at 18¢ and what they are paying to be there, and the day before Friday's sweep, comparable money went the other way. That reversal is the part of this page worth holding onto.
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The Quick Answer
As of 12:23 a.m. ET on Saturday, September 5, 2026, Kalshi prices Roger Marshall at 84¢ to buy and Adam Hamilton at 18¢ to buy for the November 3 Kansas Senate election. Hamilton's bid sits a cent under his ask, Marshall's two cents under. Friday's session traded 115,498 contracts, the most in the 39 sessions we pulled, and 93.5% of that was two one-second sweeps betting against the Republican that left Hamilton closing exactly where he opened and Marshall a cent lower, after a session that ranged 16¢ to 19¢. Thursday's big trades went the other way, and open interest says Friday's buyer was new money rather than someone closing out. Who took each side, the sourced record both campaigns are running on, and what a Marshall win smaller than his 2020 margin is priced at, are all below.
- The Price: Marshall 84¢ to buy, Hamilton 18¢ to buy, a book a cent wide on Hamilton and two cents wide on Marshall; Hamilton closed Friday where he closed Thursday and Marshall a cent lower
- Friday's Sweep: 78,069 Hamilton contracts bought in one second at 3:28 p.m. ET for $13,784, then 29,952 Marshall contracts sold at 83¢ less than a minute later
- Thursday's Mirror: 28,971 Hamilton contracts sold at 17¢ and 25,000 Marshall bought at 83¢, eight seconds apart, late Thursday afternoon
- The Money Was New: open interest on the Hamilton contract rose by 80,882 on a day that traded 84,638, so Friday's buyers opened positions instead of unwinding them
- Next Date: the two candidates debate at the Kansas State Fair on September 12 at 1:30 p.m.
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These are market prices and model estimates, not predictions of fact and not financial advice. Kalshi is a CFTC-regulated event-contract exchange (18+; availability varies by state).
The Board Right Now
| Contract | Cost to buy (ask) | Bid | Last trade | Open interest |
|---|---|---|---|---|
| Roger Marshall (R) Wins | 84¢ | 82¢ | 82¢ (a 29-contract print after the session close) | 130,842 |
| Adam Hamilton (D) Wins | 18¢ | 17¢ | 18¢ | 264,387 |
Prices are from the Kalshi trade API at 12:23 a.m. ET on Saturday, September 5, 2026. The cost to buy is what a new buyer pays right now; the bid is what a seller gets.
The row to sit with is the second one, and not for the price. Hamilton's contract carries 264,387 open positions against Marshall's 130,842, double the Republican's, in a race the market calls better than four-to-one for the Republican. Every one of those open positions has a buyer and a seller behind it, so the split says nothing about which way the money leans. It says which contract traders use to express the race: the Kansas bet gets made on the Democrat's line, in both directions, in size, and lately in single seconds.
The Market At A Glance
| Venue | Kalshi, a CFTC-regulated event-contract exchange (18+; availability varies by state, as of September 2026) |
| The Event | The November 3, 2026 general election for Kansas's U.S. Senate seat: incumbent Republican Sen. Roger Marshall against Democrat Adam Hamilton, with Libertarian David Graham also on the ballot |
| How It Settles | Each contract is priced by party. The Republican contract pays $1 "if a representative of the Republican party is sworn in as a Senator of Kansas for the term beginning in 2027," and the Democratic contract reads the same way for Democrats. Because both are party contracts, a David Graham win would settle both to No, which is why the two asks add to 102¢ rather than 100¢. Kalshi can settle early once media organizations project the winner |
| What A Cent Means | 18¢ to buy Hamilton means $100 becomes about $555 if he wins and $0 if he does not, before Kalshi's trading fee |
| Snapshot | Prices at 12:23 a.m. ET, Saturday, September 5, 2026; trade tape covers Wednesday, September 2 through Friday, September 4 |
These are live market prices, not predictions of fact and not financial or voting advice. This article does not advocate for or against any candidate or party.
What Traded In One Second On Friday
The whole Friday session is in the table below, because seven fills in one second are easier to believe when you can see them.
| Time (ET), Friday Sept. 4 | Contract | Side | Contracts | Price |
|---|---|---|---|---|
| 3:28:11 P.m. | Hamilton | Bought | 25,000 | 18¢ |
| 3:28:11 P.m. | Hamilton | Bought | 21,811 | 17¢ |
| 3:28:11 P.m. | Hamilton | Bought | 10,000 | 18¢ |
| 3:28:11 P.m. | Hamilton | Bought | 8,996 | 18¢ |
| 3:28:11 P.m. | Hamilton | Bought | 5,000 | 17¢ |
| 3:28:11 P.m. | Hamilton | Bought | 4,262 | 18¢ |
| 3:28:11 P.m. | Hamilton | Bought | 3,000 | 18¢ |
| 3:29:04 P.m. | Marshall | Sold | 24,999 | 83¢ |
| 3:29:04 P.m. | Marshall | Sold | 4,953 | 83¢ |
Fills inside a single second have no order, so the table lists them by size. The seven Hamilton fills add up to 78,069 contracts: 51,258 at 18¢ and 26,811 at 17¢, for $13,784 in total. The two Marshall sells are the same bet from the other door, since selling Marshall at 83¢ is buying "Marshall does not win" at 17¢, and those 29,952 contracts cost about $5,092. Put together, one trader or a very coordinated pair spent roughly $18,876 in 53 seconds on a position that pays about $108,021 if Hamilton is sworn in.
The number I keep coming back to is what happened to the price, which is almost nothing. It ticked as high as 19¢ within the following hour's 105 contracts and came back to 18¢, and that is the entire footprint of the sweep. A market that absorbs 78,069 contracts of buying at its ask and closes at the same 18¢ has a seller, or several, resting more than 50,000 contracts of patience at that level. That depth is the real information on the Hamilton side: someone is happy to hand out the Democrat at 18¢ in any quantity. Open interest tells the other half. The Hamilton contract's open positions rose by 80,882 on a session that traded 84,638, so almost every contract that changed hands was a fresh position for both the buyer and the seller, not an old one being closed. Friday was new money meeting new money at a price neither side wanted to move.
The Day Before, Comparable Money Faced The Other Way
The reversal the opening promised came at 5:24:53 p.m. ET on Thursday, September 3, when two fills sold 28,971 Hamilton contracts at 17¢, and eight seconds later two more fills bought 25,000 Marshall contracts at 83¢. Call it a pro-Marshall pair of 53,971 contracts, built exactly the way Friday's pro-Hamilton pair was built, one leg on each contract within seconds.
The economics of the two days are worth setting side by side. Thursday's trader paid about $44,796 across both legs to make roughly $9,175 if Marshall wins, which is the profile of someone who thinks 83¢ is cheap for an incumbent Republican in Kansas. Friday's trader paid about $18,876 to make roughly $89,145 if Hamilton wins, the profile of someone who thinks 18¢ is cheap for a challenger polling within a few points. Both can be wrong. Only one gets the whole ticket.
Together those two afternoons rewrote this market's volume history, at least the part of it we can see. In the 39 sessions of daily candles we pulled, July 28 through September 4, no single side had traded more than 11,676 contracts in a day before Thursday. Thursday traded 68,094 across both contracts and Friday traded 115,498. The 24-hour figure that flagged this market for us, 114,999 contracts at our pull, is 20.8% of the 551,659 it has traded since it listed in December 2024.
What I cannot give you is a headline that explains either afternoon. Two rating houses' Kansas entries carry a Thursday, September 3 date in the race's forecast table, Inside Elections at Likely Republican and RealClearPolitics at Lean Republican. Whether either entry was a move toward Hamilton or a reaffirmation I could not confirm, since both outlets' pages blocked my fetch, and Thursday's big pair was pro-Marshall in any case, which is not how a market reacts to a race being called closer. No poll, endorsement or wire story landed in the 3:28 p.m. minute on Friday that I could find. The honest read is that the tape does not settle what moved these traders, only that they were large, opposite, and comfortable at the same price.
What The Polls Say
Every general-election poll of this race so far has come from a Democratic-aligned pollster, which is the first thing to know before reading the numbers.
| Pollster | Field dates | Sample | Marshall | Hamilton |
|---|---|---|---|---|
| Global Strategy Group (D) | Aug. 12-16 | 800 LV | 43% | 44% |
| Public Policy Polling (D) | Aug. 7-8 | 569 | 46% | 45% |
| GBAO (D), Listed Elsewhere As GQR | July 8-13 | 600 LV | 47% | 43% |
| Tavern Research (D) | Jan. 28 | 1,013 LV | 54% | 46% |
The second row is the one the market's August move tracked most closely. Public Policy Polling's survey for Senate Majority PAC, reported by the Sunflower State Journal on August 12, had Marshall 46% to Hamilton 45% with 9% undecided, and it put Marshall's approval at 38% against 47% disapproval. Hamilton's contract closed at 22¢ that Wednesday, the day the poll was reported, and Marshall's at 78¢, the incumbent's lowest close in our window, matched the day before. A Global Strategy Group poll fielded August 12 through 16 had Hamilton a point ahead outright, and the market did not follow: the Democrat's high close was 23¢ on August 16 and the price has drifted down since.
The forecasters moved once and stopped. In the days after the primary, Cook Political Report and Sabato's Crystal Ball both shifted Kansas from Safe or Solid Republican to Likely Republican, and Fox News made the same move on August 18. Sabato's Kyle Kondik put the case for caution in one sentence: "So this is definitely a long shot, although Hamilton out-raised incumbent Sen. Roger Marshall (R-KS) $3.7 million to $610,000 last quarter." Cumulatively Marshall still has the bank, $4.78 million cash on hand through June 30 to Hamilton's $2.60 million in FEC filings, so the out-raise is a quarter, not a position. Kansas last elected a Democrat to the Senate in 1932. An 18¢ price is the market agreeing with the word "long shot" while pricing the shot a little shorter than the ratings do.
Where The Price Has Been Since The Primary
| Date (Session Close, ET) | Hamilton (D) | Marshall (R) | What happened |
|---|---|---|---|
| Aug. 4 | 16¢ | 85¢ | Primary day: Marshall 79.9%, Hamilton 34.8% of an 11-way field |
| Aug. 8 | 20¢ | 81¢ | Post-primary drift; Cook and Sabato shifts to Likely R reported by Aug. 9 |
| Aug. 12 | 22¢ | 78¢ | PPP poll reported: Marshall 46, Hamilton 45 |
| Aug. 16 | 23¢ | 79¢ | Hamilton's highest close; GSG poll fielding |
| Aug. 21 | 20¢ | 84¢ | Marshall a cent under his 85¢ pre-primary close |
| Aug. 28 | 18¢ | 83¢ | The drift settles |
| Sept. 3 | 18¢ | 84¢ | Thursday's pro-Marshall pair |
| Sept. 4 | 18¢ | 83¢ | Friday's pro-Hamilton sweep |
More live boards: the full 2026 Senate board, where Kansas sat at 83.5¢ against an 82% panel read · the 2026 Senate control board, a Republican Senate 53¢ to buy · every open board on the prediction markets hub.
Read the table top to bottom and the shape is a hill. Hamilton climbed seven cents in the 12 days after the primary, peaked at 23¢ on August 16, and gave five of them back over the next 12 days, closing at 18¢ every session from September 1 through Friday. Marshall's contract is the mirror: down seven cents to 78¢ by August 12, back to 84¢ by August 21, and between 81¢ and 84¢ since. Kalshi's own politics account posted the race at Marshall 80%, Hamilton 20% on August 12, within a couple of cents of that week's closes of 78¢ and 20¢ to 22¢. Everything since has been a slow reversal of that August move, and the two big afternoons this week landed on a price that had been pinned at 18¢ since the start of the month. That stillness is what makes Friday's size stand out: the money arrived after the argument, not during it.
The Record Both Campaigns Are Running On
Seven documented items sit behind the ad war, and the tape says the market has never traded a single one of them. Both campaigns are already on the air against each other, KWCH reported on August 18, Hamilton's spots saying "Marshall votes for tariffs and war" and Marshall-side spots calling the pastor "Way too woke for Kansas." Here is the record on both sides, with sources, and next to each item what the price did.
Marshall, three items. In March 2025 he left a Saturday town hall in Oakley about 45 minutes into a scheduled hour after telling the crowd "if you keep interrupting me, I'm going to leave," KAKE reported; his office said "Democrat operatives who couldn't place Oakley, Kansas on a map before today sabotaged a local town hall — even still, Senator Marshall stayed and answered every question that was asked for 45 minutes." That predates this market's run entirely. In June, after Hamilton raised a 2025 Kansas law under which a Senate vacancy after May 1 and before October 2 of an election year lets an appointed replacement skip the election for two years, Marshall answered on the record, per KMUW: "I am ruling out any appointment in the Trump administration at least through the next two or two or three years." And on August 31, during a telephone town hall, he said he was "frustrated" by President Trump's beef imports but called them necessary, KCUR reported; the Hamilton contract traded 2,006 contracts that session and closed a cent higher at 19¢.
Hamilton, four items. In April the Kansas GOP's executive director filed a Federal Election Commission complaint alleging Hamilton "blatantly used the corporate resources of the church" to promote his February exploratory video, KMUW reported; the church called the video the "regular way significant information is shared with our congregation," and no FEC action has been reported. In July, Kansas Reflector reporting carried by HPPR found former church employees split on his leadership and revisited a 2005 report that a church volunteer had touched boys at a church camp, which the church handled with an internal inquiry that proved inconclusive; when a second accusation came in 2006 the church reported it to authorities immediately, the volunteer pleaded guilty to misdemeanor sexual battery in 2013 and died in 2015, and Hamilton now says he "would have handled the 2005 incident differently by going directly to law enforcement." Both of those predate our candle window. In August a Main Street Fund ad called him a "woke megachurch CEO," and HuffPost's fact-check found no evidence for its claim that church funds paid for "drag queen story time for kids" and reported the ad spliced a sermon line from words about 200 words apart; the Hamilton contract traded 1,151 contracts on August 15 and closed at 22¢. And Sen. Ted Cruz called a 2022 Hamilton sermon on non-Christians and heaven "heretical," to which the campaign told the Christian Post on August 17 that "Adam was not speaking of universalism" but "was discussing inclusivism"; that session traded 1,410 contracts and closed at 22¢.
Now price it. The three items that fall inside our candle window never produced a session over about 2,000 contracts on the Hamilton side, against the 9,769 the poll week printed on August 12 and the 84,638 Friday printed on nothing at all. Five of the seven were public before August 16, the day Hamilton's contract peaked at 23¢, and the market's answer to that record was a seven-cent rise followed by a five-cent retreat; the two later items landed on a price already drifting and did not interrupt the drift. The pattern fits a race the market sees as a fundamentals question, a Republican state against a well-funded challenger, rather than one waiting on a revelation. Hamilton's own framing on primary night, as KWCH quoted it, was that "Tonight Kansans said they had enough of the chaos and corruption in Roger Marshall's Washington DC." The price puts roughly one chance in five on that reading and four in five against it.
The Margin Ladder: A Marshall Win Smaller Than 2020
Kalshi also runs a side market on how big a Republican win would be, and it says something the winner market cannot. Think of it as the market betting on Marshall's margin rather than his name.
| Republicans Win By | Cost to buy | Bid | Last trade |
|---|---|---|---|
| 3 Points Or More | 82¢ | 77¢ | 78¢ |
| 5 Or More | 70¢ | 63¢ | 63¢ |
| 7 Or More | 48¢ | 44¢ | 46¢ |
| 9 Or More | 35¢ | 29¢ | 33¢ |
| 11 Or More | 24¢ | 15¢ | 17¢ |
| 13 Or More | 17¢ | 9¢ | 11¢ |
| 15 Or More | 13¢ | 4¢ | 13¢ |
Start at "11 or more," last traded at 17¢, though a buyer today pays 24¢ to get on. Marshall won this seat in 2020 by 11.43 points, 53.22% to 41.79% over Barbara Bollier. The ladder prices a repeat of that margin somewhere between one chance in four and one in six, with the thin-book caveat below, while a win of any size sits at 84¢ on the main board. Read together, the two markets say the same thing from two angles: Marshall is the heavy favorite to win, and the ladder's buyers expect him to win by less than he did last time. The "7 or more" rung, last at 46¢, is close to a coin flip on whether he clears seven points, and "9 or more" at 33¢ says roughly two chances in three that the margin stays under nine. Rungs run on up to 23 points, but nothing above 15 has traded more than a few hundred contracts.
One caution the table cannot show. These rungs are thin: the largest holds 1,539 open contracts, the whole ladder traded 125 contracts in the last 24 hours, and the gap between bid and ask runs five to nine cents on most rows. The winner market absorbed 78,069 contracts in a second without moving; a few hundred contracts would move any row here. Treat the ladder as a considered opinion from a small room, not as a price you could trade in size.
What Each Side Costs Now
A winning contract pays 100¢, and the price is the market's implied probability. The Kalshi explainer covers the foundation, and the fee guide covers what the exchange keeps: a standard trade costs 0.07 times the contract count times the price times one minus the price, rounded up to the cent.
Run this week's two traders through that formula and the fee lands almost identically per contract, about a cent, because a 17¢ contract and an 83¢ contract sit the same distance from the middle of the board. Friday's buyer owes about $1,090 in fees on 108,021 contracts, which is 1.2% of the $89,145 profit if Hamilton wins but 5.8% of the $18,876 staked. Thursday's trader owes about $533 on 53,971 contracts, which is 5.8% of the $9,175 profit if Marshall wins but 1.2% of the $44,796 staked. The fee is a wash between the two sides; it only looks lopsided depending on whether you measure it against the stake or the win. What it does mean is practical: on a board this lopsided the fee is a real drag on small-stake long-shot money and a rounding error on the favorite's.
The book both of them met is a cent wide on Hamilton, 17¢ bid to 18¢ ask, and two cents wide on Marshall, 82¢ to 84¢, which is tight for a race 59 days out. The habit underneath all of this, reading a price against the specific question it answers and the size that set it, is the same one our sports tools are built around: find the gap between a price and fair value, then act on the gap rather than the narrative. The Kansas race is not carried on OddsShopper, but if you want to watch that method run on this week's games, our free expert picks are the place to start.
What Moves This Next
The first scheduled test of the 18¢ price is the debate. The campaigns confirmed to the Sunflower State Journal that Marshall and Hamilton will meet at the Kansas State Fair on Saturday, September 12, at 1:30 p.m., carried by WIBW radio and the Kansas Radio Network. A market that did not move on a one-point poll or a 78,069-contract sweep is telling you it wants a reason, and a debate in front of a live fair crowd is the first one on the calendar.
The second thing to watch is the next block. This market has now shown it can take 25,000-contract clips in either direction at the same price, and whichever side prints the next one will say more about where the big money is leaning than any single poll. The last date is the one the contract actually settles on: the winner is sworn in for the term beginning in 2027, with Kalshi able to settle earlier once the media consensus calls the race on the night of November 3. For how this seat fits the national count, the 2026 Senate control board prices a Republican Senate at 53¢ to buy, and the balance-of-power board prices every chamber path in one place.
In Summary
The price in Kansas finished its argument in mid-August. Hamilton went from 16¢ to 23¢ on a primary win and a one-point poll, gave most of it back, and has closed at 18¢ every session this month. What changed this week was the size of the conviction on both sides of that number: $44,796 late Thursday afternoon that Marshall's 83¢ is cheap, then $18,876 on Friday afternoon that Hamilton's 18¢ is, and after all of it the same 18¢ and 84¢ to buy. Open interest says the Friday money was new. The margin ladder's buyers expect a smaller win than 2020. The one line that would change this page is 18¢ failing to hold after September 12, and the tape has just shown how much buying it takes to test it.
Every price cited here is publicly graded once the markets settle, on our prediction market scoreboard, and the rest of the 2026 map is on our every-board Senate tracker.
