The number people look for first is the multiplier. Nikkei 225 options settle at Option Price × JPY 1,000. Nikkei 225 mini options settle at Option Price × JPY 100 — one tenth the size.
Everything below is from the Osaka Exchange contract specifications. Where the two products differ, both are shown.
| Nikkei 225 Options | Nikkei 225 mini Options | |
|---|---|---|
| Underlying | Nikkei Stock Average (Nikkei 225) | |
| Contract unit | Option price × JPY 1,000 | Option price × JPY 100 |
| Exercise | European — exercisable only at expiry | |
| Settlement | Cash, against the SQ value | |
| Trading hours | 08:45–15:45 and 17:00–06:00 JST | |
| Tick size | JPY 1 at or below JPY 300; JPY 5 above | |
| Strike interval | JPY 125 across ±24 strikes for the nearest three months; JPY 250 across ±16 further out | JPY 125 across ±24 strikes |
| Expiry cycle | Monthly (nearest 8) plus quarterly months out to eight years | Weekly Friday expiries, plus Wednesday expiry contracts |
| Last trading day | The business day before expiry day | |
| Launched | June 1989 | May 2023 (Wednesday expiries from May 2025) |
A regular Nikkei 225 option quoted at 250 costs JPY 250,000 per contract (250 × 1,000). The same quote in mini options costs JPY 25,000.
Because settlement is cash against SQ, an in-the-money call pays (SQ value − strike) × JPY 1,000 per contract, and a put pays (strike − SQ value) × JPY 1,000. Out-of-the-money contracts expire worthless.
The night session matters more than newcomers expect. Trading runs to 06:00 JST, which covers the entire US cash session, so Nikkei options price US moves before Tokyo reopens.
Monthly contracts expire on the second Friday. If that Friday is an exchange holiday, expiry moves backwards to the preceding business day — not forwards. The last trading day is the business day before that, so in a normal month the last trading day is the Thursday.
March, June, September and December are Major SQ months, when index futures expire alongside options. The settlement price is computed from the opening prices of all 225 constituents, which is not the same as the index’s own opening print. How SQ actually works covers the mechanics.
Mini options add weekly Friday expiries and, since May 2025, Wednesday expiry contracts. Something is expiring most weeks, not just on the second Friday.
For the nearest three months, strikes are listed every JPY 125 across ±24 strikes, with additional on-demand strikes available on application. In practice the listed chain runs far into the tails: on 4 September 2026 the September series carried 298 distinct strikes, spanning well below and well above spot.
That matters when you read open interest. The largest open interest in a series often sits at a round number a long way out of the money — a legacy hedge rather than a level the index is likely to reach. Gamma exposure and the put/call ratio both need that filtering.
Specifications are published by the Osaka Exchange; daily open interest, settlement prices and implied volatility come from JPX files that are free to download. Where to get Nikkei 225 data lists the filenames and publication times.
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