Tools chosen: kalshi_direct kalshi_related fred claude_news code_execution polymarket_related

Sub-questions (Fermi decomposition)

Planner reasoning

This is a long-horizon macro question about calendar-year 2028 US real GDP growth falling in a 0.4pp-wide bucket (1.6-2.0%). The key inputs are the current Kalshi prices across all buckets in the KXGDPYEAR-28 event (which imply a full distribution), official long-run projections (Fed SEP longer-run ~1.8%, CBO, IMF, Blue Chip), and the historical base rate of annual real GDP growth landing in that band including recession frequency over a 3-year horizon.

# Event US real GDP growth in 2028 resolves YES if BEA year-over-year real GDP growth falls between 1.6% and 2.0% (Kalshi ticker KXGDPYEAR-28-B1.8). # Outcomes to forecast - Yes (growth 1.6%–2.0%) - No (growth outside 1.6%–2.0%) # Kalshi market anchor Current YES price: **12.00%** (KXGDPYEAR-28-B1.8). Flat over 7 days (+0%), up +5pp over 30 days. Price range 5%–12% over 15 data points — trending upward. Avg daily volume 716 contracts — moderate liquidity. [kalshi_direct] # Sub-question answers 1. **Kalshi bucket prices** — Only this bucket's data was returned directly (12%); other KXGDPYEAR-28 buckets not retrieved (series query returned "0 markets, skipped 100 no-signal"), so full implied distribution across buckets is unavailable. [kalshi_direct] 2. **Official long-horizon projections** — Fed SEP median 2028 growth: Dec 2025 = 1.9% (range 1.8–2.1%), March 2026 = 2.1% (range 2.0–2.3%), June 2026 = midpoint 2.15% (low 1.8%, high 2.3%). CBO (Jan 2026): ~1.8% avg for 2027–2028. IMF: no direct 2028 US figure; 2026 US growth ~2.1%. Indiana Univ. Kelley long-range: 2025–2028 avg 1.95%. Consensus clusters 1.8–2.1%, straddling the top of the 1.6–2.0% bucket. [claude_news, FRED GDPC1CTM/CTH/CTL] 3. **Historical base rate** — 1950–2024: 5/75 years (6.7%) in [1.6,2.0]. 1990–2024: 5/35 years (14.3%). 1985–2024: 12.5%. [code_execution] 4. **Recession probability in 2028** — No direct 2028 recession estimate found; related Kalshi market prices "Recession in 2027" at 27% (down from 51% 30 days ago). No 2028-specific recession market found. [kalshi_related] 5. **Earlier-year analogues (2026/2027)** — Not directly retrieved; closest analogues are 2035/2036 buckets: KXGDPYEAR-35-B1.8 (same 1.6–2.0% bucket) priced at 14%, KXGDPYEAR-36-B2.8 (2.6–3.0% bucket) at 5%. No 2026/2027 GDP-year bucket data returned. [kalshi_related] 6. **Recent actuals/potential growth** — BEA annual real GDP growth: 2022=2.5%, 2023=2.9%, 2024=2.8%, 2025=2.1% (partial/estimate). Fed longer-run GDP growth estimate (GDPC1RLLR) stable at 1.7-1.9%; median longer-run (GDPC1MDLR) at 2.0% as of June 2026. Quarterly GDPC1 levels show continued growth through mid-2026. [FRED] # Key facts (high-confidence, factual) 1. [kalshi_direct] YES price 12%, up 5pp in 30 days, flat in 7 days. 2. [claude_news/FRED] Fed SEP median for 2028 growth ranged 1.9–2.15% across Dec 2025–June 2026 meetings; central tendency low bound 1.8–2.0%. 3. [claude_news] CBO Jan 2026 projects 1.8% avg growth for 2027–2028. 4. [FRED] BEA actual growth: 2023=2.9%, 2024=2.8%, 2025=2.1%. 5. [FRED] Fed longer-run real GDP growth estimate (potential) ~1.7-1.9%, stable since 2023. 6. [code_execution] Empirical base rate of landing in [1.6,2.0]%: 6.7% (75-yr) to 14.3% (35-yr recent). # Cross-market signals - Kalshi related: Recession-in-2027 market at 27% (down sharply from 51% a month ago) — suggests near-term recession risk fading, which would push 2028 growth toward trend/potential (~1.8-2.1%), overlapping top of this bucket. - Kalshi related: Analogous 1.6-2.0% bucket for 2035 priced at 14% (vs 12% for 2028) — roughly consistent pricing across horizons. - Polymarket: No matching GDP/recession 2028 markets found. - Sportsbook implied: N/A. # Analyst opinions and speculation - Deloitte: growth cooling from 2.0% (2026) to 1.8% (2027), trajectory implies continued deceleration into 2028, potentially into or near the 1.6-2.0% band. [claude_news] - IMF global growth 2028-31 avg 3.1%, but no explicit US 2028 figure; US-specific figures (2.0-2.1% for 2025-26) suggest gradual moderation. [claude_news] - Synthesis view (code_execution): mixture-model central estimate ~10-14% probability of landing in bucket, broadly aligning with Kalshi's 12% price. # Directional lean per outcome - **Yes (1.6-2.0%)**: Supported by CBO's 1.8% central estimate, Fed SEP low-end (1.8%) and longer-run estimates (1.7-1.9%), and empirical recent base rates (12-14%). Kalshi price (12%) sits near model/historical consensus. - **No**: Supported by Fed SEP medians trending higher (1.9-2.15%) and recent actuals (2.1-2.9%) currently running above the bucket; also downside risk (recession pushing growth below 1.6%) not separately quantified but plausible given elevated recession pricing for 2027. # Gaps / unknowns - Full KXGDPYEAR-28 bucket distribution (all thresholds) not retrieved — cannot fully cross-check bucket coherence/arbitrage. - No direct 2028-specific recession probability estimate. - No 2026/2027 Kalshi GDP-year analogues retrieved for direct historical bucket-pricing comparison. - IMF's explicit US 2028 figure missing from search results. # Calibration anchors - Kalshi current YES price: **12%** (primary anchor). - Historical base rate (1990-2024): 14.3%; full 75-yr sample: 6.7%. - Model-based (mixture): ~11.6%; consensus forecasts (Fed/CBO) cluster 1.8-2.1%, i.e., mostly at or above upper edge of bucket — modest lean toward "No" if central forecasts prove accurate, but wide uncertainty bands keep Yes plausible near 12-15%.

1. Both forecasts converge almost exactly (13.0% Yes) despite claimed independence, essentially just restating the Kalshi price plus a 1pp premium without meaningfully engaging with the tension noted in the brief—that Fed SEP medians (1.9-2.15%) and recent actuals (2.1-2.9%) actually skew probability mass above the bucket, which should arguably pull Yes below 12%, not above it. 2. Neither forecast decomposes the "No" outcome into its two very different tails (below 1.6% via recession vs. above 2.0% via continued trend growth), despite the brief explicitly flagging recession risk as a distinct unquantified driver ("Recession in 2027" at 27%, down from 51%)—this asymmetry could shift the distribution's shape in ways that matter for adjacent buckets, and ignoring it means both forecasts may be under- or over-estimating tail mass without justification. 3. Both forecasters uncritically treat the 1990-2024 base rate (14.3%) and 1950-2024 base rate (6.7%) as comparably informative, but neither addresses why recent decades might be more/less relevant given structural potential-growth shifts (Fed's ~1.7-1.9% longer-run estimate)—a more careful treatment would weight the recent-era base rate higher and could justify a probability closer to 14% rather than 13%. 4. The brief notes the "Recession in 2027" market fell sharply (51%→27%) which should mechanically raise the credibility of central/trend forecasts (1.8-2.1%) landing in or near the bucket, yet both forecasts cite this only as a vague "downside risk" without updating toward a higher Yes probability that this signal seems to imply. 5. Neither forecaster flags the missing full bucket distribution (other KXGDPYEAR-28 buckets weren't retrieved) as a material gap that could reveal mispricing or arbitrage; both anchor confidently on the single 12% price without acknowledging that adjacent-bucket data could corroborate or contradict this specific bucket's coherence. 6. Both confidence levels (0.66, 0.59) seem arbitrary and are not tied to any stated criteria in the rationale—given how tightly both estimates cluster around the Kalshi price with minimal independent divergence, the confidence should perhaps be more explicitly justified by bucket-width/forecast-error reasoning (0.4pp bucket vs ~1.3pp historical 2-year-ahead RMSE) rather than asserted at the end.

12% (62% confidence)

Yes: 12% No: 88%

The 1.6–2.0% band is only 0.4pp wide against roughly 1.3–1.5pp of two-year-ahead forecast error, so even with consensus (CBO 1.8%, Fed longer-run potential 1.7–1.9%) sitting inside or at the top edge of the bucket, a normal-density calculation gives only ~11–13% mass. Kalshi's 12% is corroborated by the recent-era base rate (12–14%), the analogous 2035 bucket at 14%, and the mixture model (~11.6%). The critique correctly notes offsetting pressures — the fading 2027 recession pricing (51%→27%) supports trend-like growth near the bucket's upper edge, but Fed SEP medians of 1.9–2.15% and recent actuals of 2.1–2.9% place substantial mass just above 2.0%, so these largely cancel rather than justifying a move above the market. I therefore settle essentially at the market anchor, 12.5% Yes, rather than the slight premium both forecasters applied.

Total pipeline time: 105.1s