Direct answer
Change in open interest in forex refers to how the reported total number of open contracts or open positions (open interest) changes between two points in time. In practice, it is used as a descriptive “activity” measure: it can indicate whether more positions are being added to the market or whether existing positions are being closed.
Explanation and mechanics
Open interest is a count-based metric associated with a particular market instrument and reporting venue—commonly a futures market—where “open” means not yet closed. Change in open interest is simply the difference between open interest at time A and open interest at time B.
Key material assumptions and limitations for this definition:
- It relies on what the specific data source reports as open interest for that instrument.
- It is not the same as trade volume. Volume counts activity in a period; open interest tracks the number of outstanding positions.
How it can “work” conceptually:
- If open interest increases, that suggests new contracts or positions were added net of closures.
- If open interest decreases, that suggests net position closures.
How this relates to interpretation within a change-of-character mindset:
- Change in open interest is often treated as context for whether market participation is expanding or contracting.
- Observing open interest change alongside price behavior can help describe a possible shift in market character (for example, whether participation is building or fading). Open interest change alone does not establish that a shift will continue.
Example checks (independent verification)
You can verify the calculation step without needing any trading forecast:
- Record open interest from the same instrument from two timestamps (or reporting dates) from the same data feed.
- Compute the difference: ΔOI = OI(new) − OI(old).
You can also perform consistency checks:
- Confirm the instrument and venue match across the two points in time.
- Ensure you are using the same reporting convention (for example, whether the metric is tied to futures contracts rather than spot).
If ΔOI and price move in tandem or in opposition, treat it as descriptive evidence rather than proof of future direction.
Limitations and risks
- Data comparability: open interest change depends on the instrument and reporting system, so results may not transfer across venues or between futures and spot.
- Non-predictive nature: even when open interest change aligns with a narrative about participation, it cannot reliably predict future price on its own.
- Timing effects: open interest is usually updated on a reporting schedule, so short-term inferences may be misleading.
- Inference uncertainty: increases or decreases can reflect multiple underlying behaviors (opening new positions, closing existing ones, or rolling), which cannot always be disentangled from the open interest series alone.
For readers doing independent analysis, the safest approach is to treat change in open interest as one input that describes market positioning changes, then qualify any conclusions with verification against price action and the specific data definitions used by the source.