Open interest in the COT report, explained

The short definition

In a Futures Only report, open interest is the number of futures contracts that have been entered into and remain open. In a Combined report, the CFTC converts option positions with exchange-supplied delta factors and adds them to futures positions. The result is delta-adjusted futures-equivalent open interest, not a count of option contracts. The official calculation is described in the CFTC’s Legacy explanatory notes.

If a market has open interest of 100,000 contracts, there are 100,000 open longs and 100,000 open shorts. There are not 200,000 contracts. The two sides describe the same set of outstanding contracts from opposite perspectives.

How open interest changes

Every futures trade matches a buyer with a seller, but a trade does not always create a new contract. Open interest depends on whether the matched participants are opening or closing positions.

Volume and open interest therefore answer different questions. Volume counts contracts traded during a period. Open interest counts contracts still open at the measurement point. A market can record heavy volume with little net change in open interest when positions mainly pass from one trader to another.

Why the report has two equal sides

The COT report divides the long and short sides of open interest among trader categories. Where Spreading is shown separately, the Long and Short fields show the positions left after equal long and short amounts are placed in Spreading. Add Spreading to both sides to recover the category’s contribution to long and short open interest.

Hypothetical example: the following numbers show the same open interest of 100,000 contracts from the long and short sides.

Nonreportable positions are the remainder after the CFTC subtracts all reportable positions, including Spreading where shown, from each side of open interest. The report gives neither a trader count nor a commercial classification for that remainder. That is why “nonreportable” should not automatically be read as “retail.”

Percent of open interest

Raw contract counts are difficult to compare across markets and across long periods of changing participation. The percentage fields divide each published Long, Short or Spreading position by total open interest. In the hypothetical example, 24,000 non-commercial Long represents 24% of 100,000 open contracts.

This normalization answers a useful question: how large is the position relative to the current market? It still does not describe contract value, leverage, risk or the historical rarity of the position. For historical context, compare the same category with its own past or use a clearly defined measure such as the COT Index.

CFTC percentages are rounded, so displayed values may not add to exactly 100%. Read each percentage as its own field. Spreading still belongs to both sides of open interest.

These published fields are not a net-position percentage. Net % of open interest is calculated separately: 100 × (Long − Short) / open interest. The net-position guide explains when that calculated ratio is useful.

Futures Only versus Combined

A Futures Only report uses futures positions. A Futures and Options Combined report first converts option positions into futures equivalents using delta factors supplied by the exchanges. Long calls and short puts become long futures-equivalent exposure; short calls and long puts become short futures-equivalent exposure. The CFTC then adds those values to the futures positions.

Combined open interest is therefore not a simple count of futures contracts plus option contracts. It is delta-adjusted futures-equivalent open interest, and its percentage fields use that total as the denominator. Because of option-delta calculations, a reconstructed long or short side may be one contract above or below reported futures-equivalent open interest. Keep Futures Only and Combined series separate when comparing history.

The report edition and table layout are separate choices. Legacy and Disaggregated reports are available in long and short formats. TFF is long format only, while the Supplemental report is short format only. The report-types guide explains these choices in more detail.

Open interest and price

Compare the direction of price with the direction of open interest. The four combinations below describe what changed; they are not trading signals:

Rising open interest is often described as expanding participation, while falling open interest is described as contraction. To see how reported groups changed within that market total, inspect Long, Short and Spreading separately. Every new futures contract still creates one long side and one short side.

Open interest shows how many contracts remain open, not whether longs or shorts will profit.

A practical reading order

1. Confirm the report format. Check whether the table is Futures Only or Futures and Options Combined.
2. Read the date. COT open interest is normally a Tuesday snapshot, not a live number. The report is generally released on Friday.
3. Compare with the previous report. Note whether total open interest expanded or contracted.
4. Inspect the components. Find which trader categories changed their Long, Short or Spreading positions.
5. Add scale and history. Use percent of open interest for current market share, then compare the category with its own historical range.
6. Write the observation first. Record what changed, then compare it with price and other market context.

For the complete workflow around these fields, continue with How to read the COT report. For the difference between a category’s Long and Short fields, see COT net positions explained.

What open interest cannot tell you

• Whether price will rise or fall next.
• Why an individual trader opened or closed a position.
• How much capital, leverage or risk sits behind each contract.

Read open interest beside trader categories, weekly changes, historical positioning and price. Together they describe the setting more clearly than the market total alone.

Official CFTC sources

The definitions and report mechanics in this guide follow the CFTC’s explanatory notes and its overview of the COT reports. All numerical examples on this page are hypothetical.

Common questions