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United StatesThe previous issue left two questions for this one. The first was whether the Senate binary, which at the certified reading of 26 October had given back the whole of the previous week's rise and stood at 64.50%, would climb again. The second was whether the Senate seats book would give back the mass it had moved to the band of 47 Republican seats or fewer. Both answers came out in the same direction. The contract on Democratic control of the Senate began the week of 26 to 30 October by touching 64.50% on 26 October at 01:00 UTC and swung between 65.50% and 66.50% until Wednesday. On Thursday it touched 68.50%, the previous top of the series, from 22 October; at 03:00 UTC on Friday it passed it for the first time, at 69.50%, and on Friday morning it climbed in steps: 70.50% at 13:00 UTC, 71.50% at 14:30 and 72.50% at 16:00 UTC. That value had never appeared in the series recorded since 14 April, and the contract on Republican control touched 27.50% at the same instant, the floor of the whole series. Friday's close was 70.50% and 29.50%, with the pair summing to 100.00% at both edges, so raw and normalised say the same number: 3.00pp for each side since the close of 23 October. In the distribution of Republican Senate seats, the band of 47 seats or fewer gave back nothing. It went from 40.63% to 47.88% of the book's mass, and its raw price touched 49.50% on 30 October at 15:30 UTC, the highest in that band's series, recorded since 29 July. What changed in shape is where that mass came from: last week the 48 and 49 seat bands stood still, and this week they gave way together, from 27.72% to 23.69%. The share of the bands in which Republicans end up with 49 seats or fewer, with no majority even with the Vice President's tie-break, rose less, from 68.36% to 71.57%. In words: the two Senate books moved together for the second week in a row, and the seats book not only shifted expectations to the Democratic side but shifted them within it, from the tight bands to the widest one. The seats book sums above 100% and is therefore read by shape and never by level, and no number from it is compared with the binary's price. It received USD 0.89M of new money in the week, four times the previous week's.
1.Executive Summary
The three numbers above are of different natures and do not combine. The first two are contract prices, read live and confirmed by a double reading 8 minutes apart, with a tolerance of 0.20pp. The third is an arithmetic average of published polls, in a 30 day rolling window. This issue, the last before the election of 3 November, measures how each of them behaved in the week of 26 to 30 October, with the delta anchored to the previous Friday's close, 23 October, and it refuses the subtraction between them.
2.Why this brief does not subtract the market from the poll
On the eve of the vote, the trading desk question arrives with both control contracts at the highest point of their series: if the market paid 94.50% for Democratic control of the House and 72.50% for the Senate, and the poll average for the House gives a Democratic advantage of 7.77 points, do the readings agree? The answer is still that the question has no numerical answer, for two reasons. The first is one of units, and it holds for either chamber. The second is specific to the Senate: there is no national poll that measures the vote for it, because only a third of the seats are up and each one is a state race.
Subtracting 7.77 from 93.50 would produce the number 85.73, which is not a probability, is not a vote point and would change in size if the poll were expressed on another scale, for example as a share of the two party vote. The 2012 case is the short historical example: Democrats won more House votes and fewer seats, because converting votes into seats depends on geography and on district design. This brief reports the two readings side by side and never the difference between them.
What can be compared this week, and it is not a subtraction either, is the behaviour of two books from the SAME market on the Senate: the binary on control and the distribution of Republican seat bands. They are not the same measure and this house does not convert one into the other, because the band book persistently sums above 100% and therefore serves to discuss the SHAPE of expectations, never to extract a level. For the second week in a row the two agreed in direction. In the House, the seats book closed 30 October summing to 99.70%, and at that edge its shape is concentrated on one side: the bands below 215 Republican seats add up to 91.47% of the mass, and the most expensive of all is the band below 190 seats, with 40.62%. The House majority threshold, 218 seats, falls inside the 215 to 219 band, which holds 3.81% of the mass, and that is why this book does not split cleanly between the two sides, as the Senate one does.
3.Weighted scenarios for the week
The scenarios below are not narrative: they are read in the prices of contracts the market already publishes. In this issue they use the Senate control binary, the distribution of Republican Senate seat bands and the calendar contract. Every number from the distribution comes from the close of 30 October, when the book summed 101.30%, and from the edge of 23 October, when it summed 104.60%, both inside the 95% to 105% gate, and the bands are cited as a SHARE OF THE BOOK, normalised by the sum at that edge. 🔑 The rule of method: a band book summing above 100% carries overpricing, and this house measured across 757 captures of this book that the overpricing is approximately uniform across the bands. Uniform excess means that normalising preserves the internal PROPORTION, and that is why shape can be discussed. It does not mean the normalised share is a calibrated probability, and that is why no number from this distribution is compared with the binary's price. In the Senate a Republican majority is 50 seats or more, because the Vice President breaks ties, and 50 is a band of its own in this book, so all of the mass can be assigned to one side or the other.
The binary on Democratic control of the Senate closed the week at 70.50%, against 67.50% at the close of 23 October, and touched 72.50% on 30 October at 16:00 UTC, the highest value in the series recorded since 14 April. The path had two parts: until Thursday it swung between 64.50% and 68.50%, and most of the rise came on Friday, from 68.50% at midnight UTC to 72.50% at 16:00 UTC. At the certified reading of 1 November at 20:53 UTC it stands at 71.50%, after returning to 72.50% in that Sunday's readings between 06:00 and 14:30 UTC. In the seats distribution, the share of the bands in which Republicans end up with 49 seats or fewer went from 68.36% to 71.57% of the book's mass. Within it there was a swap: the band of 47 seats or fewer went from 40.63% to 47.88%, with 42.50% and 48.50% in the raw price and a series top of 49.50% on 30 October at 15:30 UTC, and the 48 and 49 seat bands, together, gave way from 27.72% to 23.69%. The 48 seat band alone went from 17.50% to 13.50% in the raw price. In words: the seats book not only concentrated expectations on the Democratic side, it began to concentrate them on that side's widest outcome, at the expense of the tight Democratic outcomes.
The binary on Republican control of the Senate closed at 29.50%, against 32.50% at the close of 23 October, and touched 27.50% on 30 October at 16:00 UTC, the lowest value in the whole series recorded since 14 April and three points below the previous floor, the 30.50% of 23 October. Before that it had risen to the week's top, 35.50%, on 26 October at 01:00 UTC. In the seats distribution, the share of the bands of 50 Republican seats or more, which is the Republican majority with the Vice President's tie-break, went from 31.64% to 28.43% of the book's mass. It gave way in both parts, again: the band of exactly 50 seats, the tie, from 10.99% to 9.38%, and those of 51 or more, from 20.65% to 19.05%. It is a change of shape, measured on the share of a book with overpricing, and not a second price for the same outcome: it says which way the seats book's expectations moved, and not by how much the probability of control changed.
The contract on the election happening on schedule closed the week at 99.50%, 1.80pp above the 97.70% of 23 October, which takes the complementary outcome from 2.30% to 0.50%. The week began on the way down: on 27 October at 11:00 UTC it touched 97.30%, the lowest value since 11 September. From 28 October it rose with pullbacks of at most 0.20pp: 98.30% at 16:00 UTC, 99.00% at 20:00 UTC and 99.50% on 29 October at 15:30 UTC, the highest value in the series recorded since 29 July. At the certified reading of 1 November at 20:53 UTC it stands at 99.45%. It received USD 0.44M of new money in the week, more than five times the previous week's, and it remains the lowest volume book of the five this brief follows.
4.Indicator Grid
| Contract | Current | Δ week | Vol USD acc. | Implied reading |
|---|---|---|---|---|
| House, Democratic control | 93.50% | +2.00pp | USD 20.01M | Flat at 91.50% from 23 to 27 October, it rose to 92.50% on 28 October and to 93.50% on 29 October at 13:30 UTC, the highest since 4 October. The pair summed to 100.00% at both edges: raw and normalised say the same. On 31 October at 07:00 UTC it touched 94.50%, the highest in the series recorded since 29 July, and the certified reading of 1 November is at that value. |
| House, Republican control | 6.50% | -2.00pp | USD 15.94M | The exact mirror of the Democratic side, with the pair at 100.00% at both edges. It went to 5.50% on 31 October at 07:00 UTC, the lowest value in the series recorded since 29 July. The House book received USD 11.52M of new money in the week, and more than half of it, USD 6.45M, was traded on this outcome, the one that gave way. |
| Senate, Democratic control | 70.50% | +3.00pp | USD 7.49M | Top of the whole series recorded since 14 April at 72.50%, touched on 30 October at 16:00 UTC. Week's floor at 64.50%, on 26 October at 01:00 UTC: an amplitude of 8.00pp across 71 readings. The pair summed to 100.00% at both edges, and so, unlike last week, raw and normalised coincide. |
| Senate, Republican control | 29.50% | -3.00pp | USD 6.53M | Floor of the whole series recorded since 14 April at 27.50%, touched on 30 October at 16:00 UTC, at the same instant as the Democratic side's top. As in the House, most of the book's new money in the week was traded on the outcome that gave way: USD 2.48M of USD 4.17M. |
| Election happens on schedule | 99.50% | +1.80pp | USD 1.32M | From the lowest point since 11 September, 97.30% on 27 October, to the highest in the series recorded since 29 July, 99.50% on 29 October at 15:30 UTC, in two days. The drop on the night of 23 October, which the previous issue recorded, was fully recovered. |
| Republican Senate seats, distribution of 11 bands | sum 101.30% at the close | from 104.60% on 23 October | USD 4.29M | Inside the 95% to 105% gate at both edges of the week, with a clean partition across the eleven bands, no overlap and no gap. It received USD 0.89M of new money in the week, against USD 0.22M in the previous one. The band of 47 Republican seats or fewer remains the most expensive in the book, now with 47.88% of the mass. |
5.Liquidity and market structure
6.Electoral calendar through Election Day
| Date | Sample | Why it matters | |
|---|---|---|---|
| 3 Nov, Tuesday | Midterm Election Day | 435 House seats and a third of the Senate | It is the only date in this grid that resolves the contracts, and it is one day after this issue. Polls close through the night, from east to west. Every price cited here is the implied probability of an outcome that becomes known from that day on. |
| 28 Oct, Wednesday | Targoz publishes a national survey on election betting in prediction markets | 1,400 registered voters, 1,118 likely voters, fieldwork 20 to 22 October | 12% of likely voters say they have bet or plan to bet on the election, and among those who have already bet the vote goes R 55% x D 43%. It is data on who trades the instrument this brief reads, and not on the price: no calculation here links it to the contracts. |
| 28 Oct, Wednesday | Report attributes to the Democratic campaign in Alaska a scheme of spoiler candidates in the Senate race | 1 state Senate race | The story came out at 19:10 UTC, citing The New York Times. The binary on Democratic control of the Senate stood at 66.50% at 17:30 UTC and was still at 66.50% at 22:00 UTC. The next day the House oversight committee, chaired by a Republican, opened an investigation into the case. |
| 29 and 30 Oct, Thursday and Friday | Trump cancels the weekend rallies in Kansas and Iowa and reverses course the next day | campaign schedule, 2 states | The cancellation was announced on Thursday. On Friday, the binary on Democratic control of the Senate rose from 68.50% at midnight UTC to 72.50% at 16:00 UTC; CBS News recorded the reversal at 17:14 UTC, and the contract stood at 71.50% at 18:00 UTC and at 70.50% at 19:00 UTC. That is the order of the timestamps, and order is not cause: the grid of readings has intervals of one to two hours, and the series does not allow us to say which market reading came before each piece of news. |
| 31 Oct, Saturday | Early vote passes 50 million voters three days before the election | national early vote count | It is turnout data, and not data on the direction of the vote. On the same day, at 07:00 UTC, the contract on Democratic control of the House touched 94.50%, the highest in its series. |
| 1 Nov, Sunday | Federal judge dismisses the Justice Department's suit to block certification of the Alaska Senate race if the Republican loses | 1 state Senate race | It is the outcome of the request the previous issue recorded on 23 October, when the calendar contract fell 1.40pp in five hours. The ruling came out at 19:11 UTC; the calendar contract stood at 99.50% at 16:30 UTC and at 21:00 UTC, and the certified reading at 20:53 UTC gave 99.45%. |
The grid above has one date that resolves a contract, 3 November, and five that resolve none. The five are included because they are verifiable and dated, and they come with the measurement alongside. The one of 30 October is the most instructive: the largest price move of the week fell on the same day as a piece of schedule news, and the grid of readings does not have the resolution to say which came first.
7.Watch list, week triggers
- The count of 3 November, and what these five contracts say until then At the certified reading of 1 November at 20:53 UTC, Democratic control of the House stands at 94.50%, of the Senate at 71.50% and the calendar contract at 99.45%, with both pairs summing to 100.00%. The next issue, of 9 November, is the first in which the control contracts will have a known outcome, and it sets the price of each one against the result.
- The band of 47 Republican seats or fewer in the Senate, at 47.88% of the book's mass It is the most expensive band in the book and the one that absorbed the advance of the last two weeks, now at the expense of the 48 and 49 seat bands. The Senate result will say in which band the distribution ended, and that comparison is made by shape: the book summed 101.30% at Friday's close, and the normalised share is not a calibrated probability.
- The Senate binary, at 71.50% at Sunday's certified reading The readings of 1 November between 06:00 and 14:30 UTC went back to 72.50%, the same value as the top of the series touched on Friday, and by 18:00 UTC it had given up 1.00pp. It was the contract with the largest amplitude of the week, 8.00pp, against 2.00pp for the House.
- The dispersion among pollsters in the generic ballot window The five rounds with fieldwork ending between 26 and 30 October run from D+4, from Harvard/Harris, to D+10, from Emerson, with Ipsos at D+6, ActiVote at D+7 and Reuters/Ipsos at D+9 among likely voters. The D+6 one is a study by Ipsos itself conducted 100% by mail, and its author describes it as about 3 points below the aggregators. Across the whole window the distance reaches 8.00 points, with the Reuters/Ipsos of 19 October at D+12 among registered voters.
8.Methodology
Prices read on AFOS's own route with the country parameter and an uncached reading, and confirmed by the capture lock: two readings 8 minutes apart, released only if they agree within 0.20pp, with the two timestamps required to be distinct. This issue's certified reading is from 1 November 2026 at 20:53:43 UTC, and the real interval between the two timestamps was 8.0 minutes. Each contract's series is read from the database backup and never from the history route, because that route caps the window at 90 days and in the Senate contract that would hide the start of the series, which is 14 April. The piece of series the daily backup does not yet cover is closed with the route's intraday points and checked by a positive control, series by series, comparing the two sources over the window in which both have data: in this issue all five series closed with identical points on both sides, and that is why every superlative here holds for the whole series and not only for what the backup already had. Closes are the last recorded point of each day, and top and floor are intraday, because a daily close hides extremes. The week's delta is anchored to the previous Friday's close, 23 October, which is the convention of this United States series, and the tool that calculates it was required to reproduce the numbers published in the previous issue before being used here. A band distribution is cited only when the book's sum falls between 95% and 105% at the edges used, and it is cited as a share of the book, normalised by the sum at that edge. A band book summing above 100% carries overpricing, and this house tests where it sits by comparing the normalised share of the book's centre against the raw sum across the series: if the centre's share falls when the sum rises, the excess is in the tail; if it rises with it, the excess is in the centre; with no clear relationship, it is approximately uniform. Measured across 757 captures of the Senate seats book, the correlation is -0.35, and across 1,159 captures of the House seats book, +0.32, both inside the range this house treats as no clear relationship, between -0.5 and +0.5. In that case normalising preserves the internal proportion, and that is why the distribution here supports statements about SHAPE and never about level, and why no share of it is compared with the price of a binary contract. The generic ballot average is a simple arithmetic mean, unweighted, in a 30 day rolling window, with one round per pollster per wave by the hierarchy likely voter, registered voter, adults, and with a wave published under another instrument, such as the ballot with the names of the district's candidates, kept out of the calculation and declared with the pollster's own wording. Book depth is not cited in this brief, by an editorial decision of May 2026.
9.Additional reading · macro coverage
The items below are the outlets and pollsters cited in the sections above, with the address of the story or document itself. Items the collection only reached through the aggregator were dropped from this list, because the aggregator's address does not point to the outlet.
- CBS News, 1 Nov · The federal judge dismisses the suit to block certification of the Alaska Senate race, www.cbsnews.com/news/judge-doj-lawsuit-alaska-senate-race-dan-sullivan/
- CBS News, 30 Oct · Live coverage of the weekend before the election, with the reversal of the rally cancellations, www.cbsnews.com/live-updates/2026-midterm-elections-campaigns-weekend-before/
- The Washington Post, 29 Oct · Trump cancels the Kansas rally and moves to virtual events, www.washingtonpost.com/politics/2026/10/29/trump-cancels-kansas-rally-before-midterm-elections-hold-virtual-events/
- The Guardian, 31 Oct · More than 50 million early votes three days before the election, www.theguardian.com/us-news/2026/oct/31/early-voting-midterms
- Fox News, 28 Oct · The report on spoiler candidates in the Alaska Senate race, www.foxnews.com/politics/mary-peltola-campaign-dems-backed-covert-scheme-field-spoiler-candidates-alaska-senate-race-report
- The Hill, 29 Oct · The investigation opened by the House oversight committee into the Alaska case, thehill.com/homenews/house/6181949-comer-investigates-peltola-senate-allegations/
- Targoz, 28 Oct · The national survey on election betting, with 12% of likely voters betting or planning to bet, www.targoz.com/market-matters-blog/2026/10/28/one-in-eight-likely-voters-has-bet-or-plans-to-bet-on-the-midterm-elections
- The New York Times, 27 Oct · How the bias of midterm polls varies by state, www.nytimes.com/2026/10/27/us/politics/midterm-polls-errors-states.html
- The Hill, 31 Oct · The six races that could decide control of the Senate, thehill.com/homenews/campaign/6185470-senate-control-midterm-six-tossups/
- Emerson College Polling · The October national poll, with a 10 point Democratic advantage among likely voters, emersoncollegepolling.com/october-2026-national-poll-democrats-hold-10-point-midterm-advantage/
- ActiVote, 30 Oct · The house's last round before the election, with 2,000 likely voters, www.activote.net/polls/generic-ballot/2026-10-30/
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