What Is a Continuous Futures Contract? Rollover, Back-Adjustment and the Prices You See

A continuous futures contract is not a contract. It is a chart series built by joining a run of expiring contract months end to end, so that one chart can show years of price history for a market whose individual contracts all expire. Sierra Chart's documentation for the feature describes a chart that joins multiple contracts into one series and takes each bar from whichever contract month was the most actively traded one on that date.

What catches traders out is the joins. Two contract months of the same market trade at different prices on the same day, so stitching them together leaves a step at every junction, and back-adjustment, the remedy Sierra Chart's feature applies, repairs that step by changing the older prices. The history on your screen is a constructed series, and knowing how it was constructed is the difference between reading a level and reading a number that was never traded.

Why can't you just chart one futures contract month?

A futures symbol names one delivery month and one year — Sierra Chart's example in its documentation is ESZ14, the S&P 500 mini for December 2014 — and that contract expires. Chart the symbol on its own and, as that page notes, the history behind it does not reach far back.

Scroll back anyway and you arrive at dates when a different month was the actively traded one. Sierra Chart's page says the bars there are usually incomplete, can render as dashes, and carry little volume. It is a real contract, correctly plotted, with nothing much in it.

The CFTC's glossary supplies the vocabulary. The front month is the nearest traded contract month, also called the spot or nearby month; the nearby delivery month is the one closest to maturity, also called the lead month; the back months are everything else, also called deferred. Sierra Chart's volume-based roll rule puts a date on the migration between them: it transitions on the day daily volume in the next contract becomes the greater of the two. That migration is why a single-symbol chart has a thin beginning, a busy middle and a thin end. Our post on when futures contracts roll over covers the schedule that drives that migration, and futures month codes explains how to read the month and year out of a symbol.

How is the rollover date chosen on a continuous chart?

The rollover date comes from a rule you select. Sierra Chart's documentation names two, a date rule and a volume rule, and its Continuous Contract list carries both, each with a back-adjusted twin, alongside an option that reuses the same contract month every year, a forward-curve option and an off switch.

Under its Date Rule option, the transition comes from a rollover rule stored per symbol in the platform's Global Symbol Settings. Under its Volume Based option, it lands on the day daily volume in the next contract becomes greater than volume in the current one, read from historical daily data. Sierra Chart's documentation rates the date rule highly for stock index futures and calls it the quicker of the two, with no cross-contract volume analysis to do, and gives the volume method to commodity futures that have no definite calendar rule. Its later comparison section widens the volume method's remit: there it covers commodity futures and, more recently, index and currency contracts, with ES, NQ, YM, RTY, 6E and 6B named. The reason given is that the volume transition in those markets follows no firm calendar date and can land a day or two either side.

A roll rule is not only a charting setting. Quantower's Futures Rollover panel applies one to the contract itself: its documentation treats a roll as a trade, where the position in the expiring contract is shut and the same exposure is taken on in a contract dated further out, which keeps expiration from ending in delivery or settlement. The panel offers three methods — By Volume, which rolls when the next contract's daily volume surpasses the current one's; Expiring Soon, which rolls when expiry falls inside a number of days you set; and Expired, which moves an already-expired contract to the current front contract. That is a different job from Sierra Chart's, which stitches expired contracts into one chart and leaves the chart's own symbol where it is.

What does back-adjustment actually do to the prices?

Back-adjustment shifts every bar before a roll by the price difference between the two contracts at that roll, so the series has no step in it. Sierra Chart's documentation states the arithmetic: on the day of a rollover, the prior day's settlement in the newer contract, less the prior day's settlement in the contract being left, gives the junction its back adjustment amount. Both figures come from the symbol's historical daily data.

The adjustment compounds backwards. At each roll, the amount for that roll and the amounts for every later roll are added together, and that total is what the earlier contract's bars are shifted by. The newest contract month in the chart is left alone. The amount is applied to the open, the high, the low and the close of each bar, so a negative total pulls all four down together.

Sierra Chart's documentation shows the figures in its own message log for an S&P 500 mini chart. At the March-to-June 2022 transition, the March contract settled at 4275.25 on 9 March 2022 and the June contract settled at 4266.75 the same day, a difference of −8.5. Walking back from there, the cumulative amounts it lists are −8.5 for the March 2022 contract, −15.25 for December 2021, −24.5 for September 2021, −34 for June 2021 and −43.75 for March 2021. Bars drawn from the March 2021 contract therefore sit 43.75 points below the prices that contract actually printed.

Settlement prices do the work here for a reason. The CFTC's glossary defines a settlement price as the daily figure the clearing organisation uses to clear trades and settle accounts between clearing members for each contract month, and names it as one of the inputs to margin calls. Each contract month either side of a junction therefore has a single defined daily figure to take the difference between.

Why do the historical prices on a back-adjusted chart keep changing?

Because every new roll adds another adjustment to everything behind it. Sierra Chart's documentation is explicit about the consequence: under a back-adjusted option, the price the chart shows for one particular date and contract month moves as the years pass. Today's active contract carries no adjustment at all, and ten years of accumulated adjustments later those same bars print somewhere else entirely.

That matters for anyone who writes levels down. A number you noted from a back-adjusted chart last quarter does not describe the same place on the chart after the next roll, and a screenshot you took is a record of the adjustment state on the day you took it. Sierra Chart's stated way to avoid the effect is to not use a back-adjusted option at all, which leaves the steps between contract months in the chart instead.

Platforms also differ. Sierra Chart's documentation notes that an adjusted chart will not match its own unadjusted chart, and will not match a chart from another service that adjusts by a different method. Quantower's rollover panel carries a related setting for your own drawings rather than for the bars: None leaves them at the expired contract's price levels, By last price shifts them by the gap between the new contract's price and the old one's, and By custom value moves them by an amount you supply.

Can you trade the prices you see on a continuous chart?

You trade the contract your chart's symbol names, and on a back-adjusted series that is only the newest segment of what you are looking at. Sierra Chart's documentation says that when you trade from a continuous chart, the order symbol is always the chart's current symbol, whether or not trade simulation mode is on.

The same holds in testing. Run a back test, or replay the chart, and the documentation says the order symbol is still the chart's current one no matter which bar's timestamp the order went in on, which is why the trade activity log files all of it under that single symbol.

The continuous feature also does not move your chart's symbol forward for you. Sierra Chart documents the rollover options as governing the historical contracts inside the chart, with a separate Automatically Rollover Futures Symbol setting for advancing the symbol itself. The CFTC's glossary names the trade that goes with it: a Switch closes a position in one delivery month and simultaneously opens a similar one in another month of the same commodity, which the glossary calls rolling forward. A chart setting changes what you see; the switch changes what you own.

How do researchers build a continuous series for a backtest?

Carefully, and they write down which method they used. Park and Irwin's 2005 AgMAS report on technical trading rules in US futures markets sets out the problem directly in its input data section: futures have a limited life span, so a long test needs a constructed series, and there is more than one way to construct it.

The approach they describe as frequently used in the literature is to link the contracts closest to expiration. They identify two problems with it. First, the gap between the old and the new nearby contract can be wide enough to leave a visible break in the series. Second, for a period after each roll, a signal computed on the new nearby contract still carries the old contract's price history inside it.

Their alternative, taken from several earlier studies, switches between dominant contracts instead: on the roll date the old dominant contract's position is closed, and the new one is entered on a signal that was computed from the new contract's own price history. They define the dominant contract as the one with the highest open interest, note that it usually but not always matches the nearby contract, and give their own roll date as the second Tuesday of the month before delivery. Their report covers 12 futures markets and finds technical trading profits declined gradually over time, with the substantial profits of the 1978–1984 period no longer available in 1985–2003.

Series construction is an assumption like any other, and a result that turns on it is a result about your data pipeline. That is the same failure mode as curve fitting in trading, reached from a different direction.

What does a continuous chart change on a funded account?

Nothing about your balance, and quite a lot about the numbers you read off the screen. A funded account here is a simulated account trading live market data, with a real payout on the profits, and its drawdown line sits a fixed distance below your highest end-of-day balance. That balance comes from your fills in the contract you actually traded, not from adjusted chart prices. A back-adjusted level from three rolls ago is a chart artefact; the stop you place from it is enforced against that line all the same.

Platform support is the other practical point. Sierra Chart's documentation says the intraday continuous chart feature is unsupported on data from the outside trading services it names — Rithmic among them — and needs its own Denali feed plus the matching exchange fee. On Rithmic specifically the page says the feature "must be considered unsupported", because Rithmic's symbols carry years as a single digit — "a severe limitation", in its words, on how much historical data can be reached. Every platform we offer reads a Rithmic connection, so that limitation applies to the feed behind your charts here. The page's own workaround is a second Sierra Chart installation pointed at its historical data service, used only for those charts.

Sierra Chart also publishes how far back the feature reaches: on historical daily charts, a maximum of 50 years with two-or-more-digit year symbols and 5 years with single-digit years, and on intraday charts 15 years and 5 years respectively. To tell which contract a given bar belongs to, its Show Rollover Dates option draws a vertical line labelled with the month and year at each transition, which is the quickest way to separate a real level from a seam. Turning that level into money takes the tick size and tick value of the contract in front of you.

FAQ

Is a continuous futures contract the same as the front month?

No. The front month, in the CFTC's glossary, is the nearest traded contract month — a real contract you can buy and sell. A continuous series splices many such contracts together, each bar coming from whichever month was the busiest one on its date, per Sierra Chart's documentation. The newest part of a continuous chart does show the current contract, which is why the two get confused.

Why doesn't my continuous chart match another platform's?

Because the two inputs that define the series are both choices. Sierra Chart's documentation says an adjusted chart will differ from its own unadjusted chart and from a chart on another service that uses a different adjustment method, and it offers both a date-based and a volume-based roll rule, which can place the junction on different days. Different roll date, different adjustment arithmetic, different history.

Does back-adjustment change old prices permanently?

It changes them again at every roll. The shift applied to a bar is the sum of the amount at its own junction and the amounts at every junction after it, so a new roll adds one more term to that sum for every bar behind it. Sierra Chart's documentation makes the consequence plain: a contract that carries no adjustment today will read at a wholly different price ten years of rolls later. Its one stated remedy is a non-adjusted option, which puts the steps back into the chart.