Constant Maturity Commodity Index (CMCI) Roll
The Formal Definition
An advanced commodity index methodology that diversifies futures exposure continuously across multiple contractual maturities (from 3 months to 3 years) rather than rolling 100% of holdings into the next front-month contract, mitigating structural contango roll yield decay.
CMCI Return = ∑_{i=1}^{M} [ w_i × (Spot Return_i + Continuous Forward Roll Yield_i) ] (Where Tenors Range 3M to 3Y)
Cole Barrett's Reality Check
The Unvarnished Bottom Line"Traditional commodity ETFs are built with an obvious flaw: they hold front-month contracts and roll them all at once every month, handing market makers an easy arbitrage while losing money to contango. Constant-maturity indexes spread exposure across the entire futures curve—three months, six months, and two years out. It breaks the front-month roll cycle and protects your capital from contango bleed."
Interactive Simulator: Test the Math
Real-World Example: Scenario Breakdown
Examining the real numbers for: A $50,000 long allocation to crude oil over a 12-month period where the futures curve was in persistent 1.2% monthly contango
| Execution Metric | Constant Maturity (CMCI) Strategy Holder | Standard Front-Month ETF Holder |
|---|---|---|
| Fee / Rate | 0.65% fund expense ratio | 0.75% expense ratio |
| Spread / Buffer | Invested in a diversified commodity ETF that distributes contract maturities across 3-month, 6-month, and 1-year tenors | Held a standard ETF that rolled 100% of its futures contracts during a single 5-day window every month |
| Execution / Status | Mitigated contango roll costs; captured the organic commodity cycle while reducing annualized roll yield drag to just 2.4% | Suffered cumulative front-month roll decay: surrendered 1.2% every single month (-13.5% annualized roll loss) |
| Total Cost / Result | Protected capital from front-month contango roll distortion | Suffered severe capital erosion from passive front-month rolling |
How Brokers Weaponize This Term
When choosing a commodity ETF (like agriculture, oil, or broad metals), check the fund prospectus for the index methodology. If the fund tracks the 'Bloomberg Commodity Index (BCOM)' or 'S&P GSCI', it rolls front-month contracts. Seek out funds utilizing 'Constant Maturity' or 'Optimized Roll' strategies to reduce contango drag.
Broker Evaluation Matrix
Cole Approves
Interactive Brokers: Provides direct market access to underlying commodity futures contracts across all curve maturities (CME, ICE), allowing traders to bypass front-month ETF roll decay.
Read Audit →Cole Flags / Avoids
Basic Mobile Retail Apps: Promotes poorly structured single-commodity futures ETFs without disclosing ongoing contango roll costs in the interface.
View Trap Details →Frequently Asked Questions
Why does contango cause commodity ETFs to lose money?
Because in contango, future-month contracts cost more than the expiring front-month contract. The ETF sells low and buys high every month just to keep its position open.
Does constant maturity eliminate all roll costs?
No. If the entire futures curve is in steep contango, roll drag will still exist, but spreading tenors across the curve significantly dampens the financial hit compared to front-month contracts.