# Open Interest

Call and put open interest at every strike, the put/call ratio near spot, max pain and the key levels.

**Open Interest** shows how many contracts are open at each strike, calls to the
right and puts to the left, colored by days to expiry. The header gives total
open interest and the put/call ratio within ±2.5% of spot. **Details** adds the
change since an earlier snapshot (**delta tf**: 15 minutes to a week, or the
session), the largest call and put strikes, and the dealer levels. Hover a
strike to see its own change.

## Practical application

![Open Interest widget, illustrative example: new puts at 26,600 and calls trimmed at 27,250 since yesterday](https://q-bitf.com/docs-img/open-interest.png "Illustrative example data, not a real session. NQ, 90-day book, change vs 1 day ago: puts +1.9K, calls +576, net -1.3K. Top calls 27,250 (24K), top puts 26,600 (22K).")

**Reading it.** The book is balanced overall: 188K calls against 185K puts.
The biggest strikes are 27,250 for calls (24K contracts) and 26,600 for puts
(22K). With **delta tf** set to **1D**, the change tells the story of the last
day: puts grew by 1.9K, most of it at 26,600 (about +1,450), while calls grew by
only 576. Hovering 27,250 shows calls there fell by about 650, and 27,500 gained
about 820.

**What it means.** Traders added protection at the put wall and rolled some
calls from 27,250 up to 27,500. The floor got stronger; the ceiling moved up
and got a little thinner.

**How to use it.**

- **OI building at a put strike under price:** a level the market is
  protecting. Above the gamma flip it is more likely to hold on the first
  test; below the flip it can break more easily.
- **OI falling at the call wall:** the ceiling is weaker than yesterday. A
  break above it is more likely to run toward the next strike with new OI.
- **Use 15m or 1h during the day** to catch positions opening while you
  watch; use **1D** before the open to see what changed overnight.
- Pair it with [Greek Exposure](https://q-bitf.com/docs/widgets/greek-exposure) to see how much
  those contracts matter to dealer hedging.