Open Interest: The Hidden Signal Every NIFTY Options Trader Must Know

Updated May 2026 · By PaperBull Editorial Team

Most retail traders look at price and volume when analyzing markets. Experienced options traders add a third dimension: Open Interest (OI). It's right there in the option chain — that column with numbers like 42,35,625 — but many traders either ignore it or don't know what it's telling them. Let me change that.

What is Open Interest?

Open Interest is the total number of outstanding options contracts that have not been settled or closed. Unlike volume (which resets to zero each day), OI accumulates over time and represents real, open positions in the market.

When two new traders enter a trade (one buyer, one seller), OI increases by 1. When an existing trade is closed (buyer sells to another seller who's exiting), OI doesn't change. When an existing open position is closed out, OI decreases by 1.

Think of OI as a measure of how many people have "skin in the game" at a particular strike.

OI Buildup vs OI Unwinding

The most reliable signals are the first and third: when price moves in a direction and OI is building up, it confirms the move has genuine participation behind it.

Reading the NIFTY Option Chain for OI

Pull up the NIFTY option chain on NSE's website. The two most important things to look for:

• Highest Call OI strike: This is where maximum call selling has happened. It acts as a resistance magnet — the market often struggles to cross this level because call sellers defend it aggressively. For weekly expiry, this level often acts as the "implied cap" on NIFTY.
• Highest Put OI strike: This is where maximum put selling has happened. It acts as a support magnet — put sellers want NIFTY to stay above this level. It's the implied floor.

The zone between the highest Put OI strike and the highest Call OI strike is often where NIFTY spends most of its weekly expiry time — especially in quiet markets.

Max Pain — The Level Option Writers Want

Max Pain is the price at which the maximum number of options (both calls and puts combined) expire worthless. At this price, option buyers lose the most money while option sellers keep the maximum premium.

In Indian weekly expiry markets, there's a visible tendency for NIFTY to drift toward the Max Pain level in the last 1-2 days before expiry, especially if IV is low and there's no strong directional catalyst. This isn't manipulation — it's just the natural gravity of large open positions pulling the market toward equilibrium.

Max Pain is published on websites like Sensibull, Opstra, and NSE India's own option chain page. Check it every Wednesday for Thursday expiry — if NIFTY is significantly away from Max Pain with one day left, be cautious about holding directional positions.

Put-Call Ratio (PCR) — Market Sentiment Gauge

The PCR divides total Put OI by total Call OI: PCR = Total Put OI / Total Call OI

• PCR above 1.2: More puts than calls — market may be oversold, contrarian bullish signal
• PCR between 0.8 and 1.2: Balanced market, no strong signal
• PCR below 0.8: More calls than puts — market may be overbought, contrarian bearish signal

Important: PCR is a contrarian indicator. Very high PCR (everyone is buying puts, very pessimistic) often marks market bottoms. Very low PCR (everyone is buying calls, very optimistic) often marks market tops. Use it alongside other signals, not in isolation.