Corn COT Index: 10 Years of Extreme Positioning
On September 15, 2026, Managed Money funds held +414,460 net long contracts in corn (ZC), the largest long since the data began in 2006. Commercial traders were on the other side, with a COT Index of 0. Six weeks later corn has fallen from 543 to 455 cents per bushel, and funds have cut their long by more than half. When were there such extremes over the past 10 years, what followed, and what does seasonality say? We checked every week since October 2016.
How we read the Commercials COT Index
Commercials in corn are grain merchants, processors (ethanol, feed and starch producers), exporters and farmers hedging their crop. The CFTC COT report shows their net position (long minus short contracts) every week. They are usually net short, because they sell forward the crop they buy from farmers. The raw number says little on its own, so we put it into context with the COT Index.
COT Index = (current net position − 156-week minimum) / (156-week maximum − 156-week minimum) × 100
An index above 90 means Commercials are close to their largest net long (or smallest net short) position of the past three years. An index below 10 means the opposite: they are selling aggressively and are near their largest net short position. You can see the index for every market in our free COT demo.
10 years of corn: how often we reach an extreme
From October 25, 2016 to October 20, 2026 there are 522 weekly COT reports for CBOT corn. Of these:
- 53 weeks with the index above 90, in 8 separate periods;
- 61 weeks with the index below 10, in 10 separate periods.
The index spends 78% of the time between 10 and 90. The longest periods sit in the middle of big trends. Below 10 lasted 29 weeks, from October 27, 2020 to May 11, 2021, while corn rose from about 400 to 773 cents. Above 90 lasted 19 weeks, from October 31, 2023 to March 5, 2024, while the price fell to about 400 cents.
The two extreme readings tell the same story. On January 26, 2021, Commercials held their largest net short of the period, −505,016 contracts, with the price at 532 cents. By May 7, 2021, corn had climbed to 773 cents. On February 20, 2024, they were net long +282,468 contracts, with the price at 419 cents. The price fell further to 400 cents in March and only then rose to 465 cents by late May.
In corn, Commercials rarely catch the exact top or bottom. Their extreme position shows that the trend has matured, not when it will end.
What follows the first week in the zone
To test this in numbers, we ran a backtest. We take the first week in which the index enters a zone, with at least 26 weeks between two signals of the same type. Entry is the close on the Friday after the report date (when the CFTC publishes it). We measure the price change after 4, 8, 13 and 26 weeks and compare it with the average change for all weeks in the period. Corn rolls to a new front month five times a year (March, May, July, September, December), and the gap between old and new crop is often large, so prices are back-adjusted at every roll.
| Report date | Index | 4 wk | 8 wk | 13 wk | 26 wk |
|---|---|---|---|---|---|
| Above 90 | |||||
| 11/14/2017 | 95.2 | −2.0% | −2.3% | +3.7% | +8.9% |
| 04/16/2019 | 94.1 | +3.1% | +20.3% | +17.8% | +4.1% |
| 04/28/2020 | 91.5 | +4.9% | +2.1% | +4.4% | +28.6% |
| 08/15/2023 | 93.1 | −3.5% | −0.1% | −5.4% | −20.2% |
| 04/16/2024 | 91.2 | +2.4% | +1.8% | −9.5% | −10.7% |
| Below 10 | |||||
| 03/06/2018 | 4.3 | +0.6% | +3.2% | −5.4% | −14.3% |
| 06/18/2019 | 6.3 | −0.7% | −14.5% | −18.8% | −19.8% |
| 10/27/2020 | 3.4 | +6.8% | +11.7% | +35.5% | +83.2% |
| 03/08/2022 | 6.9 | −3.4% | −0.4% | −4.6% | −0.9% |
| 03/24/2026 | 9.6 | −1.5% | −0.7% | −11.5% | +4.9% |
The result is mixed, and we say so plainly:
- Above 90 worked in spring, not around harvest. The three April signals (2019, 2020 and 2024) were positive after both 4 and 8 weeks. The two signals from August and November (2017 and 2023) were negative, because they came with record crops. On average above 90 gave +4.4% over 8 weeks versus +0.6% for all weeks, but the average is pulled up by 2019 (+20.3%).
- Below 10 is a warning, not a sell signal. Three of five signals were negative after 4 weeks, but only by 0.7% to 3.4%. The strongest drop (−14.5% over 8 weeks in 2019) came after the USDA acreage report of June 28. The biggest failure was October 2020: Commercials sold while China bought record volumes and the price nearly doubled.
- The latest episode is not in the table. The index fell below 10 again on August 25, 2026, but that was less than 26 weeks after the March signal, so we do not count it as new. From the August 28 close, the back-adjusted price was −1.4% after 4 weeks and −14.9% after 8 weeks. The front month fell from 512 cents to 456 cents on October 23.
For comparison, the average change for all weeks is +0.2% over 4 weeks, +0.6% over 8, +0.9% over 13 and +1.9% over 26 weeks. The sample is small: 5 signals in each zone in 10 years. This is context for a decision, not a statistically proven system.
Seasonality in these periods
The average seasonal curve for the last 10 years (2016 to 2025) follows the US crop cycle:
- January to mid-February: a rise to about +3%;
- March to late April: sideways, then a climb to about +6% by the end of April, before planting;
- May and the first half of June: the high of the year around June 16 (about +8%), as the market pays a weather risk premium;
- late June to early September: the steepest decline, to about −4% around September 1, as the crop becomes clear;
- September to year end: a slow recovery to about +1% at the end of October and about +2.5% at the end of December.
The 15-year curve has the same shape, with a peak around May 1 (about +7%), a low around September 30 (about −2.5%) and a year end at about +1%.
Weeks below 10 are most common from March to May (30 of 61), when funds buy weather risk ahead of planting. Weeks above 90 are spread evenly across the year (1 to 6 per month).
Comparing the October 27 close with the end of December for each of the last 10 years, the price ended higher in 5 of 10 years. The median is −0.7%. In this window seasonality gives no direction.
Where we are now
According to CFTC data as of October 20, 2026:
- Commercials net position: −261,080 contracts (COT Index 28.4);
- 4-week change: Commercials have reduced their net short by 213,731 contracts;
- Managed Money net position: +164,423 contracts (156-week index 67.6), down from +414,460 on September 15;
- open interest: 1,835,658 contracts.
This is the most interesting detail. The August and September rally came from the USDA's August yield cut (by 2.3 bushels per acre, to 180.7), heat and disease in the Corn Belt. On October 9, however, the USDA raised the yield to 181.2 bushels per acre and forecast a record crop of more than 16 billion bushels. The price fell to its lowest level since mid-August, and funds have sold for five straight weeks.
The daily chart shows the full cycle. From the 12-month low (402 cents on June 29, 2026), corn climbed to 543 cents on September 21. Today's close is 455 cents, 16% below the peak, right at the 200-day average (456 cents) and below the 18-day average (481 cents).
The three frameworks currently say:
- COT: the index is 28.4 and rising fast. No signal under our filter. Funds are still long, but leaving.
- Seasonality: neutral to year end; in 5 of 10 years the price was higher.
- Price: a downtrend since September, below the 18-day average, right at the 200-day.
The scenario we are watching: if the index reaches 90 during harvest and with a record crop, it would resemble 2017 and 2023, when the signal did not work. An above-90 signal in spring, before planting, has historically been more reliable.
5 mistakes when working with COT extremes in corn
- Buying on an index above 90 at harvest. In 2017 and 2023 record crops overpowered positioning.
- Selling on an index below 10 when a new buyer is in the market. In 2020 and 2021 China bought record volumes and the price doubled while Commercials sold.
- Ignoring USDA reports. The biggest moves after signals came after the end-of-June acreage report and the monthly WASDE reports.
- Comparing old-crop and new-crop prices without adjustment. On the July to September and September to December rolls the front-month price can move several percent in a day.
- Large size on a small sample. 10 signals in 10 years are not statistics. Use the risk calculator and check open interest.
How we use it in practice
In our strategy, Commercials positioning is a mandatory filter: we do not look for longs when commercial traders are at an extreme short, and vice versa. In corn the filter is currently neutral, seasonality gives no direction, and the trend is down after the record fund long. Without a COT extreme, entry comes only from price structure and risk management.
Frequently asked questions
How many times has the corn COT Index been above 90 in 10 years?
53 weeks out of 522, in 8 separate periods. The longest ran from October 31, 2023 to March 5, 2024 (19 weeks).
How many times has it been below 10?
61 weeks in 10 periods. The longest ran from October 27, 2020 to May 11, 2021 (29 weeks).
Was the September 2026 fund long a record?
Yes. +414,460 contracts on September 8 and 15, 2026 is the largest Managed Money net long since the data began in 2006. The previous record was +409,444 contracts on March 1, 2011.
How did you calculate prices and seasonality?
We use the continuous front month ZC=F, back-adjusted on the first trading day on or after the 15th of March, May, July, September and December, when the front month changes. The charts show the actual front-month price in cents per bushel.
Is this a signal to buy or sell corn now?
No. This is an analysis of historical data. The COT Index is neutral, seasonality gives no direction, and entry should always come from price and your own risk management.
Conclusion
Over 10 years, Commercials in corn were at an extreme in about 22% of weeks. Their longest extremes coincide with big trends, not reversals. The above-90 zone worked in spring, before planting, and did not work around harvest with record crops. The below-10 zone warns of weakness, but the drop comes only when the USDA confirms large supply. Today corn is coming out of a record fund long, commercial traders are neutral, and positioning gives no edge for now.
You can follow the current COT Index for corn and dozens of other markets in our free demo; weekly analyses and the full toolset are available in our membership plans.
Sources: CFTC Commitments of Traders (Legacy and Disaggregated, Futures Only), data as of 10/20/2026; Yahoo Finance (ZC=F), prices as of 10/26/2026; USDA WASDE (August and October 2026). Calculations: fmoney.eu. Trading futures involves a high risk of loss. This content is for educational purposes and is not investment advice. Past performance does not guarantee future results.