1.30%
Kalshi’s market on the I bond fixed rate Treasury sets on Nov. 1 has its middle at 1.30%, against the current 0.90% and a five-year TIPS real yield of 2.55% (2026-10-21). Its Social Security COLA ladder is for the 2028 adjustment; the 2027 COLA implied by CPI-W under SSA’s formula is 3.6%.
Kalshi market data, TreasuryDirect, FRED and BLS, pulled Oct 23, 2026, 11:07 AM ET. Updated daily.
By Arthur Angelo, PredictionScout Research · Updated Oct 23, 2026, 11:07 AM ET
Key findings
- I bond fixed rate (next reset): market middle 1.30%; 0.90% (May–Oct 2026, TreasuryDirect).
- Social Security COLA, payable for Dec. 2027: market middle 2.55556%; 3.6% implied for 2027 by CPI-W (BLS).
The markets today
“Market middle” is where the implied chance of “above X” crosses 50%.
| Market | Closes | Market middle | Contracts (chance) | Latest official figure | Contracts traded |
|---|---|---|---|---|---|
| I bond fixed rate (next reset) | 2026-11-02 | 1.30% | >0.80%: 98% · >1.00%: 97% · >1.20%: 92% · >1.40%: 6% · >1.60%: 5% | 0.90% (May–Oct 2026, TreasuryDirect) | 16,925 |
| Social Security COLA, payable for Dec. 2027 | 2027-10-13 | 2.55556% | >1.5%: 82% · >2%: 71% · >2.5%: 52% · >3%: 34% · >3.5%: 27% | 3.6% implied for 2027 by CPI-W (BLS) | 9,900 |
Market middle: for “above X” ladders, the point where the implied chance crosses 50% (prices forced to fall as the threshold rises, interpolated between rungs). Prices are the bid/ask midpoint when the spread is 10¢ or less, otherwise the last trade. Events with fewer than 500 contracts traded show “thin trading” instead of a middle, and ladders whose quoted prices contradict each other show “prices out of order”. Pulled Oct 23, 2026, 11:06 AM ET.
How the I bond fixed-rate market settles
Treasury announces two numbers for Series I savings bonds every May 1 and November 1. The fixed rate applies for the life of any bond bought in the next six months; the inflation rate changes every six months. Kalshi’s KXIBONDFIX market is only about the fixed rate, exactly as TreasuryDirect first announces it, unrounded. Later corrections do not count.
What moves it. Treasury does not publish a formula for the fixed rate. Over the past several years it has tended to sit below the five-year TIPS real yield (shown above, from FRED DFII5), so traders watch that yield in the weeks before the reset. Treasury can also leave the rate unchanged.
Worked example. The composite rate is fixed + (2 × semiannual inflation) + (fixed × semiannual inflation). Semiannual inflation for the November reset is the change in CPI-U (not seasonally adjusted) from March to September: 330.213 to 336.940, or 2.04%. If Treasury sets the fixed rate at 1.20%, the composite is 1.20% + 2 × 2.04% + 1.20% × 2.04% = 5.30%; at 0.90% it would be 4.99%. Only the fixed-rate part decides the Kalshi market.
How the COLA market settles
Social Security’s cost-of-living adjustment is the percentage rise in the average CPI-W (BLS’s index for urban wage earners and clerical workers) for July, August and September over the same three months a year earlier, rounded to one decimal. If the result is zero or negative there is no COLA. Kalshi’s KXSSCOLA market listed today is for the 2028 COLA (benefits payable for December 2027), using the first figure SSA announces in October 2027. Changes to Medicare premiums or the net check do not count.
What moves it. Only CPI-W for July to September 2027 matters, so energy and food prices in that summer matter most, along with shelter costs, which make up a large share of CPI-W.
Worked example (the 2027 COLA). CPI-W averaged 317.265 in July–September 2025 and 328.746 in July–September 2026. The rise is 328.746 / 317.265 − 1 = 3.62%, which rounds to 3.6%. A contract for “above 3.6%” on that year would resolve No. SSA’s own announcement is what settles; this is the published formula applied to BLS data.
Download the data
I bond fixed rate and COLA markets (one row per event) (CSV)
One row per live event: market middle, contracts listed and traded, and the matching official figure. No contract prices. Free to reuse under CC BY 4.0 with a link back to this page.
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Methodology
- Markets. Every open Kalshi
KXIBONDFIXandKXSSCOLAevent from the public API. - Official values. Current fixed rate from TreasuryDirect; five-year TIPS real yield from FRED DFII5; CPI-W (CWUR0000SA0) and CPI-U (CUUR0000SA0), not seasonally adjusted, from the BLS API. The COLA and semiannual inflation figures are our arithmetic under the published formulas.
- No prices in the CSV. One row per event.
- Limits. The COLA figure shown is for 2027 (already determined by CPI-W), not the 2028 COLA the market trades. Treasury has no published fixed-rate formula. SSA’s site was not reachable from our server, so the COLA is computed from BLS data. Nothing here is investment advice. Last run: Oct 23, 2026, 11:07 AM ET.
Cite this research
Suggested citation: PredictionScout. (2026, October 23). I Bond Rate and Social Security COLA Prediction Markets. https://predictionscout.com/research/i-bond-rate-social-security-cola-prediction-markets/
For a chart or news story: “Source: PredictionScout analysis of public exchange data (https://predictionscout.com/research/i-bond-rate-social-security-cola-prediction-markets/)”
The data and charts on this page are free to reuse under CC BY 4.0 with a link back to this page. Market data: Kalshi. Official data: TreasuryDirect, Federal Reserve H.15 via FRED, Bureau of Labor Statistics.
Data sources: prices and volumes come from the public APIs of Kalshi and Polymarket, with official values from TreasuryDirect and BLS. All trademarks belong to their owners. PredictionScout is independent and not affiliated with any exchange. Nothing here is investment, betting, or legal advice.
Related: Social Security depletion market · CPI markets · All research