94% — Will the total number of UK parliamentary by-elections with polling day scheduled and held in 2026 be at least 5 2026 Leader: At least 5 at 94% · Kalshi 94% · 5 contracts · $12 volume · medium confidence Updated 2026-08-10 06:41:45 UTC Tracks the leading outcome in a winner-take-all prediction market set with 5 outcomes. Why this matters: This market reflects strong confidence that the UK will hold at least 5 parliamentary by-elections before the end of 2026, with traders pricing this outcome at 93%. The probability is elevated because the Labour government under Keir Starmer faces a narrow Commons majority achieved in July 2024, creating structural conditions for vacancies through retirements, scandals, or defections. Factors that could increase the probability include potential Labour backbench rebellions or strategic exits, while a sharp drop would require unexpected stability in the Commons. The main uncertainty driver is the unpredictable timing of individual MP retirements and resignations. By December 2026, the market will resolve based on the final count of all by-elections with polling days held during the calendar year, providing clear evidence of whether the baseline expectation of frequent turnover materializes. Key factors: - Labour's working majority of approximately 3-20 seats (depending on speaker and sickness) makes the government mechanically vulnerable to by-election losses - Historical baseline: the UK averaged 6-8 by-elections annually during the 2015-2024 period, though this varies widely - Pricing shows near-identical confidence (93%) for both 'at least 5' and 'at least 6', but sharply lower confidence (80%) for 'at least 8', suggesting clustering around 5-7 expected by-elections - The market opened after the July 2024 election, so traders are forecasting typical turnover patterns under current parliamentary arithmetic - By-election frequency depends on voluntary retirements, deaths, and forced resignations—none of which follow a predictable schedule Contracts: - Will the total number of UK parliamentary by-elections with polling day scheduled and held in 2026 be at least 5 2026?: At least 5 — 94¢ Kalshi $0 (weight 0%) - Will the total number of UK parliamentary by-elections with polling day scheduled and held in 2026 be at least 6 2026?: At least 6 — 78¢ Kalshi $0 (weight 0%) - Will the total number of UK parliamentary by-elections with polling day scheduled and held in 2026 be at least 7 2026?: At least 7 — 41¢ Kalshi $4 (weight 33%) - Will the total number of UK parliamentary by-elections with polling day scheduled and held in 2026 be at least 8 2026?: At least 8 — 17¢ Kalshi $8 (weight 67%) - Will the total number of UK parliamentary by-elections with polling day scheduled and held in 2026 be at least 9 2026?: At least 9 — 3¢ Kalshi $0 (weight 0%) --- ## Methodology SimpleFunctions aggregates live YES-side prices from Kalshi and Polymarket contracts bound to this question. For binary topics the headline is the liquidity-weighted mid-price (weight = log(1 + 24h volume) × freshness, where freshness is 1.0 if updated <24h, 0.7 if <7d, 0.4 otherwise). For multi-outcome (winner-take-all) topics the headline is the current leader's price — disjoint outcomes are never arithmetically averaged. Snapshots refresh every 5 minutes during market hours. ## SF Signal - SF Index, regime, and 30d Brier calibration are computed separately and surfaced at https://simplefunctions.dev/admin/calibration. - No SimpleFunctions index / regime / calibration signal is bound to this topic yet — the headline above is market-derived only. --- *Last verified: 2026-08-10T06:20:51.572Z* By SimpleFunctions — https://simplefunctions.dev/ Cite as: "94% per prediction markets (SimpleFunctions, August 2026)" Canonical: https://simplefunctions.dev/answer/ukbyelectioncount Full data: https://simplefunctions.dev/api/public/query?q=Will%20the%20total%20number%20of%20UK%20parliamentary%20by-elections%20with%20polling%20day%20scheduled%20and%20held%20in%202026%20be%20at%20least%205%202026 Provider: SimpleFunctions — https://simplefunctions.dev