> For the complete documentation index, see [llms.txt](https://guide.laevitas.ch/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://guide.laevitas.ch/concepts/open-interest.md).

# Open Interest

{% hint style="info" %}
**Open interest (OI) denotes the number of options or futures that are opened and not closed out yet.**

There are separate OI for options and for futures.
{% endhint %}

### **How Open Interest Is Calculated** <a href="#how-open-interest-is-calculated" id="how-open-interest-is-calculated"></a>

When options are bought or sold **TO OPEN**, it **increases** the OI.

When options are bought or sold **TO CLOSE**, it **reduces** the OI.

### **Difference between Open Interest and Volume** <a href="#difference-between-open-interest-and-volume" id="difference-between-open-interest-and-volume"></a>

For example,

If an option buyer goes to the market and buys 200 call options, the volume for the day is 200 and **the Open Interest becomes 200 as well.**

If in the same day, a new seller goes to the market and sells 150 put options, the total volume for the day is 350 and **the Open Interest becomes 350.**

If before the end of the day, both the buyer (sell to close) and the seller (buy to close), the volume added will be 350 from the buyer (+200) and seller (+150). Total volume becomes 400+350 = 750.

Since there are no longer any opened and not yet closed positions, **Open Interest therefore becomes 0** as far as these two market participants are concerned.

### **Why Open Interest Matters** <a href="#why-open-interest-matters" id="why-open-interest-matters"></a>

OI helps to give a clue on what orders traders are initiating, and the general activity of the futures/ options market.

But using Open Interest alone is not enough. It is also necessary to take a detailed look into the volume of the exact orders to have a better sensing of the sentiment of the market.<br>

Related Metrics:

[Global Perps OI](https://app.laevitas.ch/details/gm_oi?variant=OI\&subInfo=c\&type=perpetual)\
[Global Futures OI](https://app.laevitas.ch/details/gm_oi_future?variant=OI\&subInfo=c\&type=future)\
[Global Options OI](https://app.laevitas.ch/details/global_HoiBreakDownByCurrency?variant=oi)