Tools chosen: kalshi_direct kalshi_related polymarket_related fred claude_news code_execution

Sub-questions (Fermi decomposition)

Planner reasoning

This Kalshi market resolves on US real GDP growth for full-year 2028 falling in 1.6%-2.0%. Key inputs are current market pricing, current GDP trajectory and forecasts, and related markets for triangulation. Since 2028 is far out, forecaster/Fed projections matter most.

# Event US real GDP growth in 2028 falls between 1.6% and 2.0% (Yes/No) # Outcomes to forecast - **Yes**: 2028 real GDP growth ∈ [1.6%, 2.0%] - **No**: 2028 real GDP growth outside that range # Kalshi market anchor **Current YES price: 10%** (KXGDPYEAR-28-B1.8) - 7-day change: +3 pp | 30-day change: +3 pp - Range over data window: 7%–12% | Avg daily volume: ~2,517 contracts - Only 4 days of data — market is young but reasonably liquid # Sub-question answers 1. **Kalshi YES price for 1.6%–2.0% GDP growth in 2028?** — 10%, up from ~7% at launch. [Kalshi direct] 2. **Consensus forecasts for 2028 US real GDP?** — Fed SEP Dec-2025 median: **1.9%** (central tendency 1.8–2.1%); CBO: **~1.8%**; SPF Q4-2025: **1.8%**; IMF flags downside risks; OMB outlier at 3.1%. [Fed SEP, CBO pub/62005, Philly Fed SPF, Fox Business] 3. **Historical base rate for 1.6–2.0% annual GDP?** — 5 of 49 years (1975–2023) = **10.2%** full sample; 5/34 post-1990 = **14.7%**; 4/24 post-2000 = **16.7%**. Years: 1990, 2002, 2007, 2013, 2016. [code_execution/BEA] 4. **Adjacent Kalshi buckets for 2028?** — Only this bucket retrieved for 2028. For context: 2030 bucket 2.6–3.0% = 12%; 2027 bucket ≤0% = 6%. Full 2028 distribution not available. [Kalshi related] 5. **Recent quarterly GDP trajectory?** — Q1-2026: +1.6% annualized; Q4-2025: +0.5%; Q3-2025: +4.4%; Q2-2025: +3.8%; Q1-2025: -0.6%. Growth slowing noticeably in late 2025–early 2026. [FRED A191RL1Q225SBEA] 6. **Recession/recovery signals for 2028?** — Tariff drag, lower net immigration, and Middle East geopolitical risks are cited downside factors. CBO and Fed both note a 2026 bounce fading to ~1.8–2.0% trend by 2027–2028. Q1-2025 contraction (-0.6%) and Q4-2025 near-stall (0.5%) suggest vulnerability. [CBO, IMF Apr-2026 WEO, Fed SEP] # Key facts (high-confidence, factual) 1. [Fed SEP Dec-2025] Median 2028 GDP forecast = 1.9%; full participant range 1.7–2.6% 2. [CBO pub/62005] CBO projects ~1.8% average real GDP growth in 2027–2028 3. [Philly Fed SPF Q4-2025] Professional forecasters median = 1.8% for 2028 4. [FRED] Most recent annual GDP print: Q1-2026 +1.6% annualized (slowing trend) 5. [code_execution] Band width = 0.4 pp = 0.27 standard deviations of typical GDP distribution (σ≈1.5–1.9%) — structurally narrow 6. [code_execution] Normal model P(1.6–2.0%) ≈ 8.5–10.6% depending on σ assumption; blended estimate ~11–13% 7. [code_execution] Post-2000 mean = 2.09%, σ = 1.86% — high volatility swamps the narrow band # Cross-market signals - **Kalshi related**: 2030 bucket 2.6–3.0% = 12%; 2027 ≤0% bucket = 6%; 2029 5.1–5.5% = 6% (no direct 2028 comparators) - **Polymarket**: No matching markets found - **Sportsbook implied**: N/A # Analyst opinions and speculation - Consensus (Fed/CBO/SPF) is unusually aligned — all point estimates fall *within* the 1.6–2.0% band, which is bullish for Yes. [Fed SEP, CBO, SPF] - OMB projects 3.1% for 2028 — a significant upside outlier that would resolve No. [Fox Business] - IMF flags geopolitical spillovers as meaningful downside risk; a harder landing would also resolve No. [IMF Apr-2026 WEO] - SPF Q2-2026 revised 2026 growth down 0.3 pp — mild contagion risk to 2028 trajectory. [SPF Q2-2026] # Directional lean per outcome - **Yes (1.6–2.0%)**: Three major independent forecasters (Fed, CBO, SPF) all have point estimates inside this exact band; recent slowdown in quarterly data is consistent with "soft landing" scenario landing here - **No**: Band is only 40 bp wide in a series with σ≈1.5–1.9% — ~85–90% of probability mass lies outside it regardless of mean; upside tail (OMB scenario, productivity boom) and downside tail (recession, geopolitical shock) both resolve No # Gaps / unknowns - Full 2028 Kalshi bucket distribution not retrieved — can't verify implied distribution sums to 100% - Policy uncertainty (tariffs, immigration, fiscal path) is unusually high for a 2028 forecast - SPF Q2-2026 revision suggests forecasts are still moving; no latest Fed SEP (post-Dec 2025) # Calibration anchors - **Kalshi current YES price: 10%** (primary anchor) - Historical base rate: ~10–17% depending on sample window - Normal model estimate: ~8.5–10.6% - Blended quantitative estimate: ~11–13% - Key tension: consensus *mean* falls squarely in band, but distributional width makes any single 40 bp bucket structurally capped at ~10–15% - **Assessment**: Kalshi at 10% is reasonable and roughly consistent with models; slight upside bias (~11–13%) given consensus clustering, but not dramatically mispriced

1. Both forecasters correctly identify the consensus clustering but neither quantifies how much weight to assign it versus pure distributional uncertainty. The brief explicitly notes the band is only 0.27 standard deviations wide (σ≈1.5–1.9%), meaning even with the mean pinned at 1.85%, the normal model yields only ~8.5–10.6% — the consensus clustering is already largely priced into the Kalshi anchor and doesn't justify much additional upside beyond ~11–13%. 2. Neither forecaster adequately weighs the unusually high policy uncertainty for a 2028 forecast. The brief cites tariff drag, lower net immigration, and geopolitical risks as active downside factors, and the SPF Q2-2026 already revised 2026 growth down 0.3 pp — this elevated forecast uncertainty widens the effective σ beyond the historical 1.86%, which further reduces the probability of landing in any single 40 bp bucket and pushes Yes slightly lower, not higher. 3. Both forecasters ignore the recent quarterly trajectory as a potential scenario-shaping input. Q4-2025 (+0.5%) and Q1-2026 (+1.6% annualized) suggest a meaningful recession-or-stagnation risk that could produce 2028 annual growth well below 1.6%, compounding the downside tail that resolves No — neither rationale explicitly addresses whether a deeper 2026–2027 slowdown followed by a partial recovery could still land in the 1.6–2.0% band. 4. The OMB 3.1% outlier is mentioned in the brief as a "significant upside outlier" but neither forecaster assigns it any explicit probability weight. If even a 10–15% chance exists that the OMB scenario or a productivity-boom variant is correct, that alone suppresses Yes by roughly 1–2 pp below what pure consensus-mean-centered models suggest. 5. Both forecasters overlook the absence of the full 2028 Kalshi bucket distribution, which is a critical gap. Without knowing whether adjacent buckets (e.g., 2.0–2.4%, 1.2–1.6%) are priced at 15–20% each, it's impossible to confirm whether the market's implied distribution is properly normalized — a lopsided distribution could mean the 10% price already reflects informed money on upside or downside tails that the forecasters aren't modeling.

12% (50% confidence)

Yes: 12% No: 88%

Kalshi anchors at 10%, normal model gives 8.5-10.6%, base rates 10-17%. Consensus clustering inside the band justifies modest upside to ~12%, but band width (0.27σ) and elevated policy uncertainty cap the upside.

Total pipeline time: 141.6s