How to read the price and open-interest chart

Two independently-scaled axes. Read direction and turning points; never read levels, gaps or crossings.

Each StockLearn F&O page carries a chart with two lines: the stock's closing price and its total futures open interest, over the last several weeks. It's a dual-axis chart, and dual-axis charts are among the easiest visualisations to over-read. This piece explains what the chart is for and where its honest limits are.

What's plotted

Price runs against the left axis, open interest against the right, over a rolling window of recent sessions. Both are daily end-of-day values. Open interest is the all-expiry aggregate, expressed in shares.

Each axis is scaled independently to fit its own series into the available height. That is the crucial detail, and the source of every misreading that follows.

Why the two lines crossing means nothing

Because the scales are independent and chosen for legibility, the vertical position of one line relative to the other is arbitrary. Price sitting "above" open interest, or the two lines crossing, is a fact about the scaling, not about the market.

Change the axis ranges and the same data produces a completely different-looking picture with the lines crossing in different places. Nothing about the underlying data has changed.

This is why the caption under our chart says it has a time axis but not a shared value scale. It's not a disclaimer for form's sake; it's the operating instruction.

What the chart is actually good for

Two things, both about co-movement over time.

Agreement or disagreement in direction. A stretch where price rises while open interest also rises is a different market condition from one where price rises while open interest falls — the same distinction the buildup states capture, but seen as a sustained pattern rather than a single day's label.

Turning points. Whether open interest turned before, with, or after price is visible on the chart in a way it isn't in a table. Whether that ordering means anything is a separate question we haven't measured — but the shape is legible.

Why the window is short

The chart covers recent sessions rather than a long history. Two reasons.

The first is that open interest over long horizons is contaminated by the lot-size and rollover effects covered in our other F&O guides — less so in shares and aggregated across expiries, but corporate actions and F&O universe changes still leave marks over a year.

The second is legibility. A dual-axis chart with hundreds of points becomes a pair of noisy squiggles where every reader sees whatever they came looking for. A few weeks is enough to show the current episode.

No indicators on it

There are no moving averages, bands, or overlays on the chart. That's deliberate. The chart's job is to show two raw series over time so you can see their shapes; adding derived lines invites reading crossovers and signals into a picture whose axes don't support that kind of reading.

The technical read on the cash-market side lives in the scanner, computed properly, on daily data, with its own methodology. Mixing the two on one canvas would suggest a relationship we haven't measured.

It's a picture, not a signal

The chart exists so that the numbers on the rest of the page have visible context — so that a rollover percentage or a buildup label sits next to the shape of the last few weeks rather than floating alone.

It is not a trading tool, and nothing about its shape constitutes a recommendation. If you find yourself drawing a line on it and concluding something, the honest response is that the chart's axes can't support the conclusion.

This guide is educational and explains how StockLearn interprets common technical indicators, using illustrative examples. It is not investment advice or a recommendation to buy or sell any security.