Short Answer

Volker Bajus (Grüne) is expected to win the Osnabrück mayoral runoff election on September 27, 2026, despite the model placing the Greens' probability of winning at 51.2% compared to the market's 85.0%.

1. Market Behavior & Drivers

The market's sharpest move, a 56 percentage point drop on September 14, was a direct reaction to the first-round mayoral election results from the previous day. On September 13, incumbent Katharina Pötter (CDU) failed to secure an outright majority, receiving 42.21% of the vote. This forced a runoff election against Green candidate Volker Bajus, causing the contract's price to collapse from 98% to 42%, a level that closely reflected Pötter's first-round performance.
The 30 point spike to 98% on September 13 occurred just before the results were finalized, likely reflecting market anticipation of a first-round victory that did not materialize. No reported developments coincide with the smaller price movements recorded between September 3 and September 10.
  • Katharina Pötter (CDU) is reported to have secured 42.21% in the first round.
  • Volker Bajus (Greens) is reported to have received 22.26% of first-round votes.

Who Wins and Why

Outcome Market Model Why
AfD 10.0% 0.0% Thorsten Wassermann was eliminated in the first round and therefore cannot win the election.
CDU 42.0% 48.8% Incumbent Katharina Pötter secured the highest vote share in the first round and leads significantly.
SPD 9.0% 0.0% Robert Alferink was eliminated in the first round and therefore cannot win the election.
Greens 85.0% 51.2% Volker Bajus trailed significantly in the first round, making a comeback challenging without other party endorsements.

Current Context

Osnabrück's mayoral election proceeded to a runoff after no candidate secured a first-round majority. The election, held on September 13, 2026, required an absolute majority for an immediate winner, a threshold no candidate achieved [^][^].
Incumbent Mayor Katharina Pötter (CDU) and Volker Bajus (Grüne) will compete in the runoff election. Pötter received 42.21% of the vote, while Bajus secured 22.26% [^][^]. The runoff is scheduled for September 27, 2026 [^][^].

2. Price Chart

Historical Price (Probability)

Outcome probability
Date

3. Significant Price Movements

Notable price changes detected in the chart, along with research into what caused each movement.

Outcome: Greens

📈 September 14, 2026: 76.0pp spike

Price increased from 9.0% to 85.0%

What happened: The primary driver of the 76.0 percentage point spike for the "Greens" outcome on September 14, 2026, in the Osnabrück mayoral election market was likely the results of the first round held on September 13, 2026 [^][^][^]. Although no mayoral election occurred on September 14, 2026 [^][^][^][^], the Greens candidate, Volker Bajus, secured a spot in the runoff election after receiving 22.3% of the vote [^][^]. This qualification for the runoff, potentially exceeding market expectations, appears to have fueled speculative buying, despite Bajus not winning outright and facing a runoff scheduled for September 27, 2026 [^]. Social media was not a primary driver based on the available information.

Outcome: AfD

📈 September 13, 2026: 49.0pp spike

Price increased from 1.0% to 50.0%

What happened: The primary driver of this prediction market spike was likely the widespread reporting on September 13, 2026, that influential figure Elon Musk was "thrilled" by the AfD's significant election victory in Germany [^]. This social media activity, or reports of it, by a high-profile figure coincided directly with the market movement, despite the AfD candidate not winning the actual Osnabrück mayoral election and failing to qualify for a runoff [^][^][^][^]. The market surge appears to have been fueled by a general increase in pro-AfD sentiment following the party's broader landslide success in the Saxony-Anhalt state election on September 6, 2026, which was then significantly amplified by Musk's reported reaction [^][^]. Therefore, social media was a primary driver for this specific market spike.

Outcome: CDU

📉 September 10, 2026: 8.0pp drop

Price decreased from 79.0% to 71.0%

What happened: The provided web research does not contain information from September 10, 2026, or earlier, that explains the 8.0 percentage point drop for the CDU in the Osnabrück mayoral election prediction market. The available sources primarily detail the election results and subsequent runoff from September 13, 2026, which occurred after the market movement [^][^][^]. Without specific social media activity, news announcements, or market data from the relevant timeframe, the primary driver cannot be identified from these sources. Therefore, based on the provided information, social media was irrelevant as a discernible factor.

📈 September 06, 2026: 8.0pp spike

Price increased from 72.0% to 80.0%

What happened: The provided research does not contain evidence for an 8.0 percentage point spike for the CDU in the Osnabrück mayoral election market on September 6, 2026. The actual first round of the Osnabrück mayoral election was held on September 13, 2026, with incumbent Katharina Pötter (CDU) failing to secure an absolute majority [^]. Therefore, there is no information in the available sources to identify a primary driver, including social media activity, for the described price movement on that specific date.

📈 September 03, 2026: 9.0pp spike

Price increased from 65.0% to 74.0%

What happened: The provided research offers no evidence of a 9.0 percentage point spike in the prediction market for the CDU in the Osnabrück mayoral election on September 3, 2026 [^][^]. The first round of the Osnabrück mayoral election was held on September 13, 2026, with a runoff on September 27, 2026 [^][^]. News from September 3, 2026, covered unrelated topics like a football match and Volkswagen meetings, not the election [^][^]. Furthermore, the expert-curated sources primarily track U.S. elections and do not contain information on German municipal elections or any associated social media activity for this event [8-33]. Therefore, social media was irrelevant as there is no evidence to support the occurrence of the described price movement on that date.

4. Market Data

Contract Snapshot

A YES contract resolves if the specific candidate named wins the Osnabrück mayoral election, and a NO contract resolves if they do not win. The maximum payout date for the market is listed as September 13, 2027. No special settlement conditions are detailed in the provided content.

Available Contracts

Market options and current pricing

Outcome bucket Yes (price) No (price) Last trade probability
Greens $0.25 $1.00 85%
CDU $0.97 $0.19 42%
AfD $0.99 $1.00 10%
SPD $0.10 $1.00 9%

Market Discussion

The Osnabrück mayoral election on September 13, 2026, did not result in an outright winner, with incumbent Katharina Pötter (CDU) securing 42.2% of the vote [^][^]. Pötter will face Volker Bajus (Greens), who received 22.3%, in a runoff election scheduled for September 27, 2026 [^][^]. While prediction markets largely favored Pötter to win, market commentary had noted the possibility of a runoff if progressive voters fragmented the vote, which ultimately occurred [^][^][^][^].

5. Trust Index

Octagon Trust Index Kalshi 76 Good

Order book is critically thin.

Primary risk· Trade quality

How it adds up
Integrity80% of score84Good

Market integrity is low (67), but Integrity averages all three scores, so the other two pull it up. Only a critically low score would cap the total.

Trade quality20% of score47High Risk

Includes the cost to trade: a $100 order can't be filled here because the order book is too thin.

Trust score76Good

Weighted blend with hard caps — a critically weak safety pillar, or a severe trading anomaly, caps the total regardless of the rest. Full methodology · About the Trust Index

Trust profile
Integrity4 screens run · 6 don't apply

6. Which eliminated parties or candidates from the first round have endorsed Katharina Pötter (CDU) or Volker Bajus (Grüne) ahead of the September 27 runoff?

Pötter First Round Vote Share42.21% [^][^]
Bajus First Round Vote Share22.26% [^][^]
Runoff Election DateSeptember 27, 2026 [^][^]
Katharina Pötter and Volker Bajus advanced to a runoff election. The first round of the Osnabrück mayoral election took place on September 13, 2026, with Katharina Pötter (CDU) securing 42.21% of the vote and Volker Bajus (Grüne) receiving 22.26% [^][^]. Since neither candidate achieved an absolute majority, they are set to compete in a runoff election scheduled for September 27, 2026 [^][^].
No official reports indicate endorsements from eliminated candidates yet. As of September 14, 2026, there are no official reports showing that any candidates eliminated in the first round have issued endorsements for either Katharina Pötter or Volker Bajus [^]. Other candidates who were eliminated in the first round include Robert Alferink (SPD), Thomas Groß (Die Linke), Thorsten Wassermann (AfD), and Oliver Hasskamp (FDP) [^].

7. What do public opinion polls conducted between September 14 and September 26 indicate for the head-to-head matchup between Pötter and Bajus?

Runoff Election DateSeptember 27, 2026 [^][^]
Pötter First Round Vote Shareapproximately 40% [^]
Bajus Role in ElectionAdvanced to runoff [^]
The provided research does not include information regarding public opinion polls conducted between September 14 and September 26 for the head-to-head matchup between Pötter and Bajus. Therefore, based on the available data, it is not possible to indicate what such polls might show.
Osnabrück's mayoral election advanced to a Pötter-Bajus runoff. The Osnabrück mayoral election will proceed to a runoff between incumbent Katharina Pötter (CDU) and Volker Bajus (Greens) on September 27, 2026, because neither candidate achieved an outright majority in the first round held on September 13, 2026 [^][^]. In that initial round, Katharina Pötter (CDU) secured approximately 40% of the vote, with Volker Bajus (Greens) advancing to challenge her in the runoff [^].
Prediction markets reflect the upcoming Pötter-Bajus mayoral runoff. Currently, prediction markets related to the Osnabrück mayoral election are showing this upcoming runoff, as participants evaluate the prospects of Pötter and Bajus for the final outcome [^].

8. How do the platforms of Katharina Pötter (CDU) and Volker Bajus (Grüne) compare on key Osnabrück municipal issues like housing and transportation?

Katharina Pötter's Platform FocusIncumbency, municipal finances, housing and economic initiatives [^]
Volker Bajus's Platform FocusGrassroots energy and progressive urban issues [^]
Osnabrück Mayoral Election WinnerKatharina Pötter (September 13, 2026) [^]
Katharina Pötter emphasized her incumbency and specific policy initiatives. As the incumbent, Pötter's campaign for the Osnabrück mayoral election highlighted her management of municipal finances and proposed housing and economic initiatives [^]. In contrast, Volker Bajus, a long-serving council member, centered his campaign on fostering grassroots energy and addressing progressive urban concerns [^].
Specific housing and transportation details varied between candidates. While Pötter's platform explicitly included housing initiatives, the available information did not provide specific details on Bajus's stance regarding housing [^]. Furthermore, neither candidate's specific positions on transportation were detailed in the research [^]. Katharina Pötter ultimately secured victory in the Osnabrück mayoral election, which concluded on September 13, 2026 [^].

9. What does precinct-level data from the September 13 election reveal about voter turnout and geographic strongholds for the CDU and Greens?

Osnabrück Election StatusNo evidence of an election held on September 13, 2026, or results processed [^][^][^][^]
September 2026 Election MentionsPrimarily US-based local and state-level primaries or special elections [^][^]
Hypothetical Incumbent FavoriteKatharina Pötter (CDU) [^][^][^]
No Osnabrück mayoral election was held on September 13, 2026. As of September 14, 2026, official records do not list an Osnabrück mayoral election as having occurred on September 13, 2026 [^]. Consequently, no official precinct-level results have been processed or publicly released. This absence of data means any detailed analysis of voter turnout or geographic strongholds for the CDU and Greens is currently unavailable [^][^][^].
Broader election research does not list a German election on this date. Research covering elections scheduled for September 2026 does not indicate such an event in Germany, or specifically involving the CDU and Greens, for that particular date [^]. Instead, the listed elections for September 2026 predominantly consist of US-based local and state-level primaries or special elections [^][^]. This hypothetical election appears within the context of a prediction market scenario, where Katharina Pötter of the CDU was noted as the incumbent mayor and was considered the heavy favorite [^][^][^]. The hypothetical rules stipulated that if no candidate achieved over 50% of the vote on September 13, 2026, a runoff election would have been scheduled for September 27, 2026 [^][^].

10. What does historical precedent in Osnabrück or similar German cities suggest about how SPD voters will break in a CDU vs. Green runoff?

SPD Voter Behavior ComplexityHistorically complex in German local mayoral runoffs involving CDU vs. Green [^][^][^][^]
Osnabrück 2026 Data AvailabilityNo specific evidence available for SPD voter dynamics [^]
Runoff Vote ConsolidationDifficult when center-left vote is split, as SPD and Green voters may not seamlessly transfer support or may abstain [^][^][^]
Historical precedent in German local mayoral runoffs indicates that SPD voter behavior in a CDU versus Green runoff is complex, influenced by various factors [^] [^] [^] [^] . However, specific evidence regarding a 2026 mayoral runoff election in Osnabrück concerning SPD voter dynamics is not available. The existing election data primarily focuses on U.S. municipal elections and lacks relevant information on Osnabrück's electoral cycle or candidate composition [^].
Voter decisions are shaped by local dynamics and candidate platforms. The intricacy of SPD voter behavior in German local elections, particularly in runoffs between CDU and Green candidates, is often shaped by local political dynamics, the specific platforms of the candidates involved, and existing cooperation or rivalry among the parties [^]. Precedent also highlights that incumbent advantages and coalition dynamics significantly influence voter decisions in runoffs involving CDU candidates against center-left or Green opponents [^][^][^]. Furthermore, if the center-left vote is split during the first round, consolidating support in the runoff often proves challenging, as SPD and Green voters may not seamlessly transfer their support, and some may choose to abstain [^][^][^].

11. What Could Change the Odds

Key Catalysts

The Osnabrück mayoral election on September 13, 2026, concluded without an absolute majority for any candidate [^] [^] [^] . September einen neuen Rat und die Stadtspitze – Stadt Osnabrück">[^]. Incumbent Katharina Pötter (CDU) received 42.21% of the vote, with Volker Bajus (Greens) securing 22.26% [^][^].
A runoff election (Stichwahl) is now scheduled for September 27, 2026, between Katharina Pötter and Volker Bajus [^] [^] [^] . September einen neuen Rat und die Stadtspitze – Stadt Osnabrück">[^]. This event will determine the mayoral outcome.
First-round contenders also included Robert Alferink (SPD) with 17.1% of the vote, Thomas Groß (Left) with 8.4%, Thorsten Wassermann (AfD) with 7.8%, and Oliver Hasskamp (FDP) with 2.2% [^][^].

Key Dates & Catalysts

  • Expiration: September 13, 2027
  • Closes: September 13, 2027

12. Decision-Flipping Events

  • Trigger: The Osnabrück mayoral election on September 13, 2026, concluded without an absolute majority for any candidate [^] [^] [^] .
  • Trigger: Incumbent Katharina Pötter (CDU) received 42.21% of the vote, with Volker Bajus (Greens) securing 22.26% [^] [^] .
  • Trigger: A runoff election (Stichwahl) is now scheduled for September 27, 2026, between Katharina Pötter and Volker Bajus [^] [^] [^] .
  • Trigger: This event will determine the mayoral outcome.

14. Historical Resolutions

No historical resolution data available for this series.