Open interest (OI) is the number of option contracts that are open and not yet closed (the basics are in Open interest: what it is and how to read it). Inflow is a rise in open interest at a strike over the day: new positions were opened. Outflow is a decline: positions were closed. Open interest itself shows where positions have built up over weeks; inflow shows where a large participant has just stepped in.
How inflow differs from volume
Volume is how many contracts traded during the day. Open interest is how many remain open afterwards. A thousand contracts of volume can create a thousand new positions or none at all, if some participants simply handed positions to others or opened and closed within the day.
- High volume with inflow: new positions appeared at the level. The strongest confirmation.
- High volume without inflow: positions were rolled or closed intraday.
- Outflow: participants are leaving the level.
Inflow and outflow never occur at the same strike at once. Both appear from the second day of history, since a change needs a previous report to compare with.
Showing flows on the chart
The settings are under "Contract" → "Filter". Filters work as "or": a strike is shown if it passes at least one enabled filter.
- "inflow ≥" shows strikes where open interest grew by at least the threshold over the day. The threshold is in contracts and is tuned per instrument.
- "extend right" draws the inflow line from the report date to expiration day, turning a one-day event into a level for the future.
- "to first touch" ends the line at the first candle that touches the level, leaving only untouched levels on the chart.
- "outflow ≥" shows strikes that positions have left.
Each strike gets a bar: its length is proportional to open interest, and the thicker dark part is the day's inflow.
Progress and regress
One day of inflow says little. What happens to the level afterwards matters more. The "inflow prog/regress" option follows every level that had a large inflow and assigns it a state:
- progress +N%: the position keeps growing, the level is strengthening;
- holding: open interest is almost unchanged;
- regress −N%: positions are being closed; the level is drawn dashed.
The number next to the option is sensitivity in percent: the smaller it is, the sooner a level switches to "progress" or "regress". A ribbon of daily changes is drawn above the label. With "to first touch" on, a level is dropped from tracking once price touches it.
The idea is simple: a level in progress still has money behind it. A level in regress is losing its backing even if the line on the chart still looks imposing.
Premium and breakeven
An option buyer starts making money not at the strike but further out, after recovering the premium paid. "Add premium" moves the label from the strike to that point, and "draw lines to strike" shows the whole zone in between. In that zone the buyer is still at a loss and the seller in profit; with near-dated series price often reacts to the breakeven rather than to the strike itself.
Total open interest
Besides strikes there is the day-by-day overview: "total OI & volume" under "Contract" → "More", or the separate OLIMP_SumOI panel below the chart.
- Futures. Price up with open interest up: new money is entering. Price up with open interest down: the rally is driven by short covering. Mirror image for declines.
- Options. Shows which side is building positions day to day: calls or puts.
Example: gold, early October 2026
From September 25 to October 2, gold fell 3.8%. Total open interest in the series expiring October 27 rose meanwhile: calls from 88,453 to 100,854 contracts, puts from 57,485 to 64,219.
By strike the picture is more specific. The largest call inflows were 3,064 contracts at $4,510 and 1,369 at $4,400, both above price. In puts, 2,495 contracts at $3,800. At the same time puts at the $4,400 strike saw an outflow of 1,019 contracts. So during the decline call open interest above price did not shrink but grew; the largest put inflow landed at a strike far below price; and puts that ended up deep in the money were partly closed.
None of this is visible on the price chart or in the totals, only in the strike-by-strike view. And it still does not say who the buyer was.
Questions and answers
Where can I see open interest without the indicator? On the instrument pages in Analytics: total call and put open interest and the main levels. The full strike-by-strike view and flows are in the indicator.
What inflow threshold should I set? It depends on the instrument. Raise it until 2–4 levels remain on the chart; if there are ten, the threshold is too low.
Is futures open interest the same as options open interest? No. Futures have one number per contract; options have a separate value at every strike, separately for calls and puts. The strike-by-strike view is what produces levels on the chart.
What flows do not show
- Who bought and who sold. A call inflow includes buyers expecting a rise and sellers who think price will not go above the strike.
- What happens intraday. The CME report comes out once a day with end-of-day data.
- Intent. Some inflows are hedges for other positions, not standalone bets.
So read inflow together with the rest of the picture: walls, Max Pain, PCR and the ±1σ corridor. You can try the settings on a live chart without installing anything in the indicator simulator; what exactly OLIMP draws is on the open interest indicator for MetaTrader 5 page.
This article describes open positions based on exchange data and is not investment advice.