Open Interest
Open Interest, or OI, is the total number of futures or options contracts that are currently active — i.e., have not been closed or expired. Unlike volume, which counts every trade in a session, OI counts contracts that remain open at the end of the day. Indian traders use OI alongside price action to infer institutional positioning and gauge market sentiment.
Key takeaways:
- OI counts the total outstanding F&O contracts at end of session.
- Rising OI with rising price = strengthening uptrend.
- Rising OI with falling price = strengthening downtrend.
- Falling OI with rising price = short covering rally; less reliable.
- Falling OI with falling price = long unwinding; trend losing strength.
OI vs Volume
| Volume | Open Interest | |
|---|---|---|
| What it counts | Total trades in a session | Net outstanding contracts |
| Refreshes | Each day | Carries forward |
| Best for | Liquidity, conviction | Positioning, sentiment |
Interpreting OI changes
OI changes are typically read alongside price moves. The four-quadrant interpretation:
- Price ↑, OI ↑: Fresh longs entering — uptrend likely to continue.
- Price ↓, OI ↑: Fresh shorts entering — downtrend likely to continue.
- Price ↑, OI ↓: Shorts covering — rally may not have legs.
- Price ↓, OI ↓: Longs unwinding — selling pressure may ease.
OI in Indian markets
Nifty and Bank Nifty options publish OI data live. Many traders watch the highest OI strikes (call and put) as “support” and “resistance” levels — interpretation called Max Pain. The strike with the most call OI is often resistance; with the most put OI is often support. These dynamics can shift dramatically around expiry.
Sectoral and stock OI signals
- Big OI build-ups in stock futures often signal coming corporate events.
- OI shifts among call writers and put writers indicate institutional sentiment.
- Sudden OI drops can hint at large players exiting before news.
OI and expiry day dynamics
On expiry day, OI in expiring contracts collapses as positions are closed or rolled. Traders watch the rollover of OI to the next expiry to gauge whether market participants are sticking with their views. Strong rollover with rising OI in the next series often signals continuation.
Limitations of OI analysis
- OI alone is not a signal — combine with price and volume context.
- Stock-specific OI can be skewed by small numbers of large institutional positions.
- Pre-expiry OI can mislead due to rollover dynamics.
- OI does not distinguish between long and short positions directly.
Frequently asked questions
Where can I see OI data?
NSE’s website, broker option chains, and most charting platforms display live OI.
Does Lemonn show OI?
Yes. The F&O interface on Lemonn shows OI changes alongside premium and Greeks.
What is Max Pain?
A theoretical strike at which the maximum number of options expire worthless. Many believe the market tends to gravitate towards this strike around expiry.
How often does OI update?
OI is updated by the exchange continuously and finalised at end of session.
