CORN SPECIALIST · Grain / Price Statistics
Z11353 – [C] Corn 63-Day Return Skewness Mean-Reversion
Tail-driven corn selloffs (negative return skewness) historically mean-revert; concentrated big up-days exhaust and fade.
At a glance
Current reading
+0.323
On the plus-or-minus one scale; negated 63-day skew z-score.
Signal state
Meanrev Bull
Current state across the Mean-Reversion Bull / Tail-Rally Exhaustion regime.
Phase duration
24 sessions
Consecutive trading days in the current phase.
Sample
36 years
Daily CBOT Corn returns, 1989 onward.
As of Nov 02, 2026. Updated nightly.
SIGNAL OVERVIEW
When CBOT Corn daily returns display highly positive skewness over the trailing 63 trading days, the recent price action was driven by concentrated big up-days — tail-event rallies that historically exhaust rather than continue. When skewness is low or negative, recent returns were tail-driven selloffs — historically followed by mean-reversion recoveries.
This signal captures that distributional-moment regime. It reads the 63-day rolling skewness of CBOT Corn daily returns, z-scores on a 252-day window, negates the sign so LOW skew reads as a POSITIVE composite, and bounds with tanh. The polarity inversion is empirical: raw skew has negative IC vs corn forward returns; negated skew is bullish mean-reversion. The signal is a price-statistics read, orthogonal to fundamental weather and positioning signals, and it has held sign-consistent across five decades of CBOT corn data.
LIVE CHART
Thirty-six years of the 63-day negated return-skewness composite against CBOT corn forward returns.
What the chart is showing. The dark line in the top panel is the negated 63-day return-skewness composite on a tanh-bounded plus-or-minus one scale — positive means a mean-reversion bull setup (recent returns were tail-driven selloffs), negative means tail-rally exhaustion (recent gains concentrated in big up-days). The bronze line in the middle panel is the CBOT corn front-month in cents per bushel. The bottom panel tracks the 252-day rolling information coefficient between the composite and corn 60-day forward returns. Dashed horizontal lines mark the plus-or-minus 0.2 moderate and plus-or-minus 0.5 extreme thresholds.
COMPOSITE
+0.323 / tanh
STATE
Meanrev Bull
PHASE
+0.33
SAMPLE N
9,000+ days
TODAY’S PLAYBOOK READING
STATE
Meanrev Bull
STATE AND HISTORY
Composite +0.323, state Meanrev Bull, 24 trading days running in the current phase. Per-state baselines in the regime table below.
THE SKEWNESS MEAN-REVERSION MECHANISM
High positive skewness in trailing 63-day returns means recent gains were concentrated in tail events (big up-days) — rally exhaustion. Low or negative skewness means recent returns were tail-driven selloffs — recovery setup. The signal negates raw skew so LOW skew reads as POSITIVE composite (bullish mean-reversion). Polarity is empirically determined — raw skew has negative IC on forward corn returns.
HOW TO POSITION
Price-statistics signal orthogonal to fundamental weather and climate signals. Pair with the Corn Weather Drought Composite, Corn La Nina / PDO Amplifier, and CFTC Managed-Money positioning. When all three align on direction, corn conviction is high.
WHAT THE CHART SHOWS
The composite sits at +0.323. Signal state is Meanrev Bull, 24 trading days running. See the regime table below for per-state baselines.
TOP INPUTS FIRING
- Primary composite +0.323 State Meanrev Bull, 24 trading days running in the current phase.
- Negative 63-day return skewness Recent corn daily returns show low/negative skewness — tail-driven selloffs dominant. Mean-reversion bull setup firing.
- Daily IC +0.166 p<1e-55 - Grade A confirmed Non-overlap rho +0.175 at p=0.032 — INDEPENDENTLY SIGNIFICANT. Grade A. Cross-decade sign-consistent.
THE TAKEAWAY
What this means for you today
THE MEAN-REVERSION CALL
Composite +0.323, state Meanrev Bull, 24 trading days running. Current direction and per-state baselines are in the regime table below.
THE EMPIRICAL CONTEXT
Per-state forward returns are shown in the regime table. The signal has held sign-consistent across every decade from the 1980s through the 2020s — robust across regime changes.
THE HONEST CAVEAT
The signal is bull-tilt only — it fires on the positive side (mean-reversion bull setup), with no reciprocal bearish state. Natural horizon is set by the 63-day skew window; it is a medium-term mean-reversion read, not a day-trade.
THE REGIME MAP
The three states, forward returns and sample share
Computed from 8,994 trading days. Baseline Corn fwd60d: plus 0.29 percent. Grade A directional with INDEPENDENTLY SIGNIFICANT non-overlap p=0.032 (every-60d sampling, n = 150). Bull-tilt only: signal fires on mean-reversion bull side.
| State | Phase | Share | Fwd 60d | HAC t | Edge vs baseline | Last firings |
|---|---|---|---|---|---|---|
| Mean-Reversion Bull TODAY | +1 | 36.5% (3307 d) | +2.96% | +2.67pp | Apr 2026, Mar 2025, Jul 2024 | |
| Tail-Rally Exhaustion | 0 | 63.5% (5748 d) | -1.22% | -1.51pp | Apr 2025, Dec 2024, Nov 2023 |
The historical pattern
Signature episodes in the 36-year sample
THE TRACK RECORD
State changes
| State | Start | End | Duration | Fwd 60d C |
|---|---|---|---|---|
| Strong Mean-Reversion Bull | 10/30/2024 | 12/17/2024 | 34d | +3.76% |
| Normal | 12/18/2024 | 03/24/2025 | 65d | -3.27% |
| Mean-Reversion Bull | 03/25/2025 | 04/21/2025 | 19d | +3.27% |
| Normal | 04/22/2025 | 04/13/2026 | 245d | +19.03% |
| Mean-Reversion Bull | 04/14/2026 | 04/24/2026 | 9d | +8.71% |
| Strong Mean-Reversion Bull | 04/27/2026 | 09/29/2026 | 108d | +3.22% |
| Mean-Reversion Bull | 09/30/2026 | 10/30/2026 | 23d |
Scroll inside the table for the full history. Forward 60-day C is measured from each run’s start date; a reader cannot trade off a start-date they only identify in hindsight, so this is a transparency log, not an alpha claim. Asterisked (*) returns are partial. The run is less than 60 trading days old. The full 60-day comparable fills in as more data arrives.
What this measures
Tail-driven corn selloffs historically mean-revert into recovery, and tail-driven rallies historically exhaust. The composite reads the 63-day rolling skewness of CBOT Corn daily returns, z-scores on a 252-day window, negates the sign so LOW skew reads as POSITIVE composite (mean-reversion bull), and bounds with tanh.
Why it matters
Why skewness mean-reversion predicts corn forward returns
Rolling skewness measures the asymmetry of recent return distribution. High positive skewness = big up-days concentrated in a few sessions (tail-event rally) rather than persistent accumulation. These rallies historically exhaust as the mean-reversion mechanism reasserts. Low or negative skewness = big down-days concentrated (tail-driven selloffs) which historically mean-revert into recovery. The signal captures this distributional-moment regime through 63-day rolling skewness, z-scores against 252-day baseline, and negates the sign so low skew reads positive. Cross-decade sign-consistent across five decades.
Why Grade A with independent-sample confirmation
Daily Spearman IC plus 0.166 at p-value 2.8e-56 across 8,994 observations — very strongly significant daily. Non-overlap rho plus 0.175 at p-value 0.032 across 150 independent samples — INDEPENDENTLY SIGNIFICANT. Cross-decade robustness is a key strength: 1980s strong positive, 1990s positive, 2000s positive, 2010s positive, 2020s positive — five decades sign-consistent positive.
How to use this signal today
Price-statistics signal that is orthogonal to fundamental weather and climate signals (correlation rho approximately 0 vs C Weather Drought Composite and C ENSO/PDO Amplifier). Pair with those two fundamental signals plus CFTC Managed-Money positioning and USDA WASDE flow. Current Mean-Rev Bull firing adds modest bullish bias to any directional stacked read.
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Not investment advice · The analysis on this page is informational and educational. Signal readings, historical case figures, and empirical statistics are derived from publicly available data and are provided without warranty. Hypothetical performance results have inherent limitations, including the benefit of hindsight. Readers who intend to trade should consult a licensed investment professional and see the research brief for the full disclaimer.
Last refreshed Nov 03, 2026 11:40 PM ET