Futures roll: mechanics, expiry and costs

A futures roll combines two transactions: it closes or offsets the position in the current expiry and opens a position in a deferred expiry. It does not extend the old contract and does not automatically transfer the same risk. The new future has its own price, time to expiry, liquidity, basis and settlement procedure.

What happens in the two legs

For a long position in an M1 future, a roll into M2 normally involves:

1. selling M1 to offset the existing long;
2. buying M2 to open the new long.

For a short position, the directions are reversed. The destination is not necessarily the next expiry: it can be a farther expiry specified by a mandate, index or strategy. The two legs can be executed separately or as a calendar spread quoted by the venue. A spread order can reduce the risk of a market move between legs, but it does not eliminate the bid-ask spread, slippage, commissions or partial-execution risk.

The CFTC also uses “roll-over” for moving one leg of a spread between delivery months. Every operational description must therefore state the starting position, contract closed, contract opened, direction and quantity.

Similar exposure does not mean identical quantity

Quantity, multiplier and target exposure must therefore be recalibrated. If both contracts have the same multiplier, keeping the same contract count approximately preserves sensitivity per point. It does not guarantee the same notional because the price has changed. Copying the quantity is even less defensible when multiplier, currency, specifications or the risk target change.

For a linear future, a first-level estimate is:

notional = price × multiplier × number of contracts

If the target is a notional N*, the theoretical new quantity is:

q₂ = N* / (M2 price × M2 multiplier)

Tradable quantity must be rounded to whole contracts. A mandate based on volatility, duration, DV01 or beta must instead match that sensitivity, not notional alone. None of these equivalences ensures that M1 and M2 will react in the same way: the curve can change shape and the two expiries can have different drivers.

When the roll takes place

There is no universal day. The choice can depend on:

• last trading day, first notice day and delivery calendar;
• migration of volume and open interest into the new expiry;
• spread, depth and quoted size in both legs or in the calendar spread;
• published rules of an index or fund;
• constraints imposed by the broker, clearing member or mandate;
• the risk to be maintained and the available execution window.

The front month is not always the most liquid contract. First notice day is also relevant only to contracts and procedures that provide for it: it must not be applied as a generic rule to cash-settled futures. The Futures expiry and settlement page separates these dates.

Curve differential and operating costs

Suppose M1 is at 100 and M2 at 103 at the same instant. The M2 − M1 calendar spread is 3. For a long that sells M1 and buys M2, this number describes the term structure between expiries. It is not automatically a three-point debit to the account at the time of the switch:

• realized P&L on M1 depends on its entry price and selling price, not on the quotation of M2;
• M2 opens with a new cost basis equal to the actual execution price;
• subsequent P&L depends on the path of M2;
• bid-ask spreads, commissions and slippage are actual, separate operating costs.

If M2, after being bought at 103, converges to 100 while spot is unchanged, the long loses three points on M2. If M2 instead rises to 108, it gains five points. Initial contango can therefore be a headwind relative to spot, but it does not determine total return by itself. Roll yield, changes in basis and execution cost are not synonyms.

Verifiable example

A trader is long four M1 contracts with a multiplier of EUR 20 per point. M1 is closed at 4,985 after entry at 4,950, and four M2 contracts are opened at 4,997.

The 12 points must not be mechanically subtracted from EUR 2,800: they compare two different expiries. They become economically relevant through the subsequent path of the new expiry, convergence and the methodology used to measure return. The EUR 80 in the example is instead an execution cost that can already be attributed; actual calculations must add commissions and any other applicable fees.

Continuous series: the chart jump is not the account

A series that links each front month without adjustment can show a jump on the day the symbol changes from M1 to M2. That jump comes from changing contracts and does not represent the P&L of an instrument actually held. Back-adjusted, forward-adjusted or ratio-adjusted series remove the jump under different rules and can rewrite historical levels.

For research, backtesting and signals, document at least:

• selected contract and roll calendar;
• roll price and time window;
• series adjustment method;
• weights during a multi-day roll;
• costs, collateral return and treatment of anomalous expiries.

Using a continuous series without this information can confuse tradable price changes, accounting adjustments and roll return.

Checklist before switching

• Have I identified the code, month and year of M1 and M2?
• Do I know the last day, notice period and settlement of both?
• Does the target concern contracts, notional or a specific sensitivity?
• Is the selected expiry consistent with liquidity and the mandate?
• Can I use a calendar spread, or must I manage leg risk?
• Have I separated bid-ask, commissions and slippage from roll yield?
• Does the continuous chart use a documented methodology?
• Have I checked whether the broker will close or move the position earlier?

Sources

• U.S. Commodity Futures Trading Commission, Futures Glossary — Roll-Over — moving a nearby position into a more deferred delivery month.
• CME Group, Understanding Futures Expiration & Contract Roll — offset, rollover and settlement at expiry.
• CME Group, Rolling an Equity Position Using Spreads — executing an expiry switch through a spread.
• U.S. Commodity Futures Trading Commission, Customer Advisory: Learn About Risks Before Investing in Commodity ETPs or Funds — effect of repeated rolls on returns.
• FINRA, Regulatory Notice 10-51 — curve, roll yield and divergence between futures-linked products and spot.
• Campbell & Company (white paper hosted by CME Group), Deconstructing Futures Returns: The Role of Roll Yield — linked series, roll adjustment and decomposition of returns.

Related pages

• Futures
• Futures expiry and settlement
• Futures basis
• Futures curve
• Contango and backwardation
• Roll yield
• Transaction costs
• Roll