9A.11 Participant-wise open interest
Motivation
NSE publishes, each evening, how the open interest in equity derivatives is split among four categories of participant. Commentary reads it as "what FIIs are doing". It is useful, within limits that follow from how it is built.
9A.11.1The participant file#
The file fao_participant_oi_DDMMYYYY.csv (URL in 9A.2) gives, for Client, DII, FII and Pro, the number of contracts long and short in: index futures, stock futures, index call options, index put options, stock call options, stock put options, plus total long and total short. "Pro" is brokers' proprietary trading; "Client" is everyone else trading through a broker that is not classified as FII (foreign portfolio investor) or DII (domestic institution), so it includes retail, HNIs and corporates.
Identity 9A.11
For each instrument column, total long contracts equal total short contracts across the four categories,
because every open contract has one long and one short. The 27 Oct 2026 file satisfies this exactly (for example, index futures 3,58,464 = 3,58,464; index calls 30,60,791 = 30,60,791).
9A.11.2Reading the October 2026 data#
Data (NSE participant-wise OI, contracts)
| Date | FII index fut long | FII index fut short | FII long share | Client index fut long | Client index fut short | Total index call OI |
|---|---|---|---|---|---|---|
| 5 Oct 2026 | 29,117 | 3,31,508 | 8.1% | 3,01,687 | 59,654 | 60,73,080 |
| 6 Oct 2026 | 30,285 | 3,24,010 | 8.5% | 2,97,348 | 60,248 | 35,18,112 |
| 26 Oct 2026 | 46,522 | 3,23,627 | 12.6% | 2,79,094 | 71,512 | 63,84,338 |
| 27 Oct 2026 | 33,588 | 2,54,645 | 11.7% | 2,51,789 | 57,363 | 30,60,791 |
| 5 Nov 2026 | 52,037 | 1,89,475 | 21.5% | 1,87,440 | 82,799 | 46,67,868 |
What it can tell you
- The distribution of index-futures positions: FIIs were heavily net short index futures throughout (long share 8–22%), and Clients net long. The rise of the FII long share from 8% to 22% between early October and 5 Nov is a real change in positioning.
- Day-to-day changes in a category's gross positions, net of expiry effects.
9A.11.3Limits of the file#
What it cannot tell you
- Hedges versus views. FIIs hold Indian equities worth many lakh crore rupees. A short index future against that holding is a hedge, not a bearish bet. The file has no cash-market positions; M11 · 11.12 covers FII/DII cash flows, which NSE publishes separately as provisional daily figures.
- Delta and gamma. Contracts at every strike and expiry are added. A long deep-ITM call and a long far-OTM call count the same. Nothing about dealer gamma (9A.6) can be recovered.
- Underlyings. "Index" sums every NSE index contract (Nifty, Bank Nifty and others) at their own lot sizes.
- Expiry mechanics. Index call OI fell 42% from 5 to 6 Oct and 52% from 26 to 27 Oct 2026, because the expiring series vanished, not because anyone changed their mind. Compare expiry days with expiry days, or compute changes excluding the expiring series (which this file cannot do).
- Contracts and lot changes. Counts are in contracts, so the Nifty lot change from 75 to 65 broke comparability across January 2026.