What the bhavcopy contains
The bhavcopy lists each futures and options contract that traded in the session: open, high, low and close, settlement price, contracts traded, traded value, open interest and the change in open interest. NSE publishes it once per trading day after the close, so it reflects final end-of-day figures, not live ticks.
The four buildup classes
| Price | Open interest | Class | Meaning |
|---|---|---|---|
| Up | Up | Long buildup | New buyers entering |
| Down | Up | Short buildup | New sellers entering |
| Up | Down | Short covering | Shorts closing; no new buyers |
| Down | Down | Long unwinding | Longs closing; no new sellers |
Buildup tells you whether a move came with new positions or with existing ones closing. New positions suggest stronger conviction than covering or unwinding.
Daily versus cumulative change
Daily OI change compares each day with the previous close and shows that session's flow. Cumulative OI change measures the shift from the start of your chosen window, showing the standing position built or unwound across several days. A stock with small daily changes but a large cumulative build is accumulating quietly.
A worked example
XYZ futures: Day 1 closes at 1,000 with OI of 10 lakh. Day 2 closes at 1,020 with OI of 11.5 lakh. Day 3 closes at 1,030 with OI of 10.8 lakh.
| Day | Price change | OI change | Class |
|---|---|---|---|
| Day 2 | +2.0% | +15% | Long buildup |
| Day 3 | +1.0% | -6.1% | Short covering |
Cumulative OI change from Day 1 is +8% (10.8 ÷ 10 − 1). Day 3's rise was driven by shorts closing, not new buyers, so the standing long build is Day 2's.
Illustrative numbers for a hypothetical stock, not a recommendation or a past trade.
Basis and relative strength
- Basis is the futures price minus the spot price. A widening premium can indicate bullish positioning; a discount can indicate bearish positioning, though cost of carry and dividends affect it.
- Relative strength versus NIFTY shows whether a stock's derivatives move is stronger than the index's.
- Rollover near expiry shifts OI between contracts, so compare like-for-like contracts.