Support & Resistance
Derived from Open Interest
The option chain does not just show positions — it reveals where large writers are defending price. Learn to read those levels as dynamic support and resistance.
Why option writers create price levels
Traditional technical analysis draws support and resistance from historical price action. Open interest gives you a fundamentally different and often more forward-looking source of these levels: the positions of option writers.
When a large number of traders sell (write) put options at a particular strike, they are taking on the obligation to buy the underlying if price falls to that level. If price approaches that strike, these writers face losses — so they hedge by buying the underlying or its futures, which creates buying pressure. That buying pressure is why high put OI tends to act as support.
The mirror image applies on the call side. Call writers at a strike are obligated to deliver the underlying if price rises to that level. They hedge by selling futures as price rises, creating selling pressure — which is why high call OI tends to act as resistance.
The basic rule: two strikes to watch
When you open the NIFTY option chain, two numbers stand out:
- Strike with highest call OI — treat as resistance. Writers at this strike have the most to lose if price crosses it.
- Strike with highest put OI — treat as support. Writers at this strike have the most to lose if price falls through it.
These two strikes define an implied range for the expiry. The max pain calculation formalises this by finding the point at which total losses for all option buyers is maximised — which usually sits between these two strikes.
OI concentration vs OI spread
A single dominant peak in OI at one strike signals a clear, strong level. When OI is spread across several strikes without a standout peak, the range is less well-defined and price may move more freely. Always check whether the OI is concentrated (sharp peak) or distributed (gradual rise across strikes) before assigning weight to a level.
The OI buildup patterns guide covers how this concentration shifts during the week as new positions are added and old ones rolled.
How OI levels shift during the expiry cycle
OI-based levels are not static. At the start of a weekly expiry cycle (Monday for Thursday-expiry NIFTY options), OI may be modest with many strikes attracting roughly equal interest. By midweek, a dominant strike usually emerges on each side as writers choose their battleground. On expiry day, OI can shift dramatically as traders roll positions to the next expiry.
Check change in OI (not just raw OI) to see which levels are growing in significance versus which are being abandoned. A rapidly rising change in OI at a new strike is more significant than a large OI holdover from the previous week that is not attracting fresh writing.
What happens when OI levels break
When price breaks decisively through a high-OI resistance or support level, two things happen simultaneously: option buyers who were positioned in that direction profit and add, while option writers who defended that level scramble to hedge their now-in-the-money exposure. Writers of put options that suddenly become in-the-money sell futures to hedge — which adds to downward momentum. This gamma cascade is one reason option chain levels, when they break, often produce sharper-than-expected moves.
Monitor the live OI data around key events like RBI policy, budget announcements or index rebalancings, where OI levels may be rapidly reset.
A worked NIFTY example
Suppose NIFTY is near 22,500 on a Tuesday morning (hypothetical numbers). You scan the Thursday expiry option chain:
- 22,700 call: OI = 4,20,000 contracts (highest on the call side, up 80,000 from Monday)
- 22,300 put: OI = 3,85,000 contracts (highest on the put side, up 60,000 from Monday)
- Change in OI at 22,600 call: +1,10,000 — secondary resistance forming
The read: writers are defending a primary range of 22,300–22,700 with substantial fresh positions added Monday. Secondary resistance is also forming at 22,600. A trader watching this might plan that any intraday dip toward 22,300 is likely to attract buyers (put writers hedging), and any push toward 22,700 is likely to face seller activity (call writers hedging). With NIFTY lot size of 75, the 4,20,000 contracts at 22,700 represent 3.15 crore units of notional exposure — a wall that the market would need significant conviction to breach.
Combining OI levels with PCR
The Put-Call Ratio tells you the aggregate sentiment, while OI levels tell you where that sentiment is positioned. A high PCR (more put OI than call OI overall) suggests bearish hedging across the board, but OI levels reveal the specific strikes where the heaviest defensive positions sit. Use both together: PCR for direction bias, OI levels for precise entry/exit zones.
Common mistakes
- Treating OI levels as fixed price targets rather than dynamic zones — they shift as writers roll.
- Using raw OI without checking change in OI — stale OI from the previous expiry can mislead.
- Ignoring the implied volatility context — a high-IV environment can produce wider price swings that break OI levels more easily.
- Assuming that highest OI is always at round numbers — in volatile sessions, writers concentrate wherever the current ATM happens to be.
- Watching only one expiry — monthly OI levels can differ substantially from weekly OI levels in direction and magnitude.
Frequently asked questions
How do you find support and resistance from open interest?
The strike with the highest put open interest typically acts as support — put writers there are defending that level. The strike with the highest call open interest typically acts as resistance — call writers are defending that level from above. These levels shift as OI migrates during the week.
Why does high put OI create support?
Put writers collect premium by taking on the obligation to buy the underlying if price falls below the strike. They lose money if price falls to that strike, so they often hedge by buying the underlying near those levels, which creates buying pressure and acts as support.
What happens when OI-based support breaks?
When price breaks through a high-OI support level, it often accelerates. Put writers start hedging by selling futures (delta hedging), which adds to selling pressure. This cascade is one reason sharp falls often accelerate below key OI support levels.
Do OI-based levels work on Bank Nifty?
Yes. OI-based support and resistance works on Bank Nifty option chains in the same way as NIFTY. Bank Nifty has weekly expiry and strike intervals of 100 points. Because Bank Nifty is more volatile, OI levels tend to shift more frequently and require more active monitoring.
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TradePulse highlights the highest OI strikes on both call and put sides so you can spot support and resistance at a glance.