When Is SQ Day for Nikkei 225 Options?

SQ day is the morning a Nikkei 225 option stops being a tradable contract and becomes a cash figure. SQ stands for special quotation, and the SQ value is calculated from the opening prices of the 225 stocks in the index on the second Friday of the contract month. It is an opening print settlement rather than a closing price settlement, and that one design choice shapes everything else about the session.

When is SQ day for Nikkei 225 options?

The rule is fixed, so no calendar is needed to work it out. SQ day is the second Friday of the contract month. When that Friday is a Tokyo exchange holiday, the settlement day moves earlier, to the business day before it. Monthly contracts settle on that Friday every month, and the weekly Nikkei 225 options settle on the Fridays in between, each against its own SQ value.

The expiring contract's last trading day is the business day before SQ day, normally the Thursday. Those two dates are worth keeping apart in your head. Trading in the contract ends on one day, and the number that settles it is created the next morning. A position still open at Thursday's close cannot be traded out of. It rides into Friday's opening prints. US index options carry the same structure, and our options expiration calendar sets out how those dates fall.

What does the SQ value actually measure?

Special quotation is a computed number, not a price anyone traded at. Tokyo opens each stock with a single price auction, the itayose, which matches the accumulated buy and sell orders at one clearing price. On SQ morning the exchange takes each of the 225 members' opening prices from those auctions and runs them through the index's own weighting. The result is the SQ value.

The members do not all open at the same instant. A stock that has not printed yet cannot contribute, so the final figure lands only once the last constituent has opened, usually within the first hour. A member that does not trade at all that day is represented by its base price.

Two things follow from this construction. Nobody fills an order at the SQ value, since it is a composite of 225 separate auctions. And the index itself need never print that number: a Nikkei chart on SQ day frequently never touches the level the contracts settled at.

Why March, June, September and December are Mega SQ

Four of the twelve SQ days a year are known as Mega SQ, or major SQ. They fall in March, June, September and December, the contract months of the standard Nikkei 225 futures. On those mornings the expiring futures reach final settlement against the same opening composite as the expiring options, so two markets clear through one set of auctions. The remaining eight are minor SQ, options only, and they pass with far less attention.

The US market has the same quarterly rhythm under a different name. The third Friday of March, June, September and December is triple witching, when the quarterly index futures and index options expire on the same morning as that month's single stock options.

An opening print is a different number from a close

The US listed market runs the same construction under a different acronym. The traditional monthly S&P 500 index option settles to the Special Opening Quotation, a value built from the opening price of every index member on the third Friday of the month. SQ and SOQ are one idea in two markets, which makes US opening prints a fair way to show what an opening composite is made of.

Below are the opening prints of a set of large US stocks on Friday 20 March 2026, a quarterly settlement morning, each measured against its own previous close, with the ordinary Friday a week earlier alongside for scale.

SELECT
    ticker                                                              AS symbol,
    round(100 * (toFloat64(anyIf(open,  date = '2026-03-20'))
               / toFloat64(anyIf(close, date = '2026-03-19')) - 1), 2)  AS settlement_open_gap_pct,
    round(100 * (toFloat64(anyIf(open,  date = '2026-03-13'))
               / toFloat64(anyIf(close, date = '2026-03-12')) - 1), 2)  AS ordinary_open_gap_pct
FROM global_markets.stocks_daily_aggs
WHERE ticker IN ('AAPL', 'MSFT', 'NVDA', 'JPM', 'JNJ', 'KO', 'PG', 'XOM')
  AND date IN ('2026-03-12', '2026-03-13', '2026-03-19', '2026-03-20')
GROUP BY ticker
HAVING countIf(date = '2026-03-12') > 0
   AND countIf(date = '2026-03-13') > 0
   AND countIf(date = '2026-03-19') > 0
   AND countIf(date = '2026-03-20') > 0
ORDER BY settlement_open_gap_pct DESC

Across 8 names the settlement morning prints landed between 0.75% on XOM and -0.57% on MSFT, each against its own previous close. A settlement value assembled from prints with that much spread inside it is a genuinely new number, not the previous close nudged along. In Tokyo the same arithmetic runs across 225 members instead of eight.

AM settled US index options work the same way

In the US the distinction is written into the contract. AM settled index options settle from the opening composite on their expiry Friday and stop trading the Thursday before. PM settled contracts, including the weekly index series and every listed single stock option, settle from closing prices on expiry day itself. Japan's SQ sits on the AM side of that line. AM settled versus PM settled options works through the difference, and it is the piece of intuition that transfers in either direction.

A settlement built on the open concentrates settlement related trading into the opening auction. The panel below measures that concentration in SPY: the share of a full session's volume that printed in the first regular session minute, on the third Friday of each month against that month's other Fridays.

WITH per_session AS
(
    SELECT
        toDate(toTimeZone(window_start, 'America/New_York'))            AS session_date,
        sumIf(toFloat64(volume), et_minute = 570)                       AS opening_minute_volume,
        sumIf(toFloat64(volume), et_minute >= 570 AND et_minute < 960)  AS session_volume,
        countIf(et_minute >= 570 AND et_minute < 960)                   AS session_minutes
    FROM
    (
        SELECT
            window_start,
            volume,
            toHour(toTimeZone(window_start, 'America/New_York')) * 60
              + toMinute(toTimeZone(window_start, 'America/New_York'))  AS et_minute
        FROM global_markets.delayed_stocks_minute_aggs
        WHERE ticker = 'SPY'
          AND window_start >= '2025-08-01'
          AND window_start <  '2026-08-01'
    )
    GROUP BY session_date
    HAVING session_volume > 0 AND session_minutes > 300
)
SELECT
    toString(toStartOfMonth(session_date))                     AS month,
    formatDateTime(toStartOfMonth(session_date), '%b %Y')      AS month_label,
    round(100 * avgIf(opening_minute_volume / session_volume,
                      toDayOfMonth(session_date) BETWEEN 15 AND 21), 2)      AS third_friday_pct,
    round(100 * avgIf(opening_minute_volume / session_volume,
                      toDayOfMonth(session_date) NOT BETWEEN 15 AND 21), 2)  AS other_friday_pct
FROM per_session
WHERE toDayOfWeek(session_date) = 5
GROUP BY month, month_label
HAVING countIf(toDayOfMonth(session_date) BETWEEN 15 AND 21) > 0
   AND countIf(toDayOfMonth(session_date) NOT BETWEEN 15 AND 21) > 0
ORDER BY month

In Jul 2026 the opening minute carried 1.67% of the third Friday session, against 1.13% on the month's other Fridays. The series covers 11 months back to Aug 2025, where the same pair measured 1.33% and 0.95%.

Why the open can look distorted on SQ morning

Ask about SQ on a Japanese trading forum and someone will say the open was pushed around. The mechanism is public, and it is duller than that.

Consider an index arbitrage book: a trader holds the basket of member shares against an offsetting futures position, and the futures settle at the SQ value. The only print that matches both legs is the opening auction on SQ morning. Unwinding the basket at any other time leaves a difference between what the shares fetch and what the futures pay. So those orders go into the opening auction, on both sides, in size, on a date every participant has known for months.

A single price auction clearing an unusually large book can settle away from where the stock closed the day before, and 225 of those roll into one figure. The rule is published, the timing is public, the auction takes orders from anyone, and every print in it is a real trade in real shares. The distortion is a mechanical property of concentrating flow into one moment. Reading it as manipulation mistakes a published settlement rule for a trick.

The trace below places two consecutive Friday mornings on the same clock, one ordinary and one a quarterly settlement Friday.

SELECT
    formatDateTime(toTimeZone(window_start, 'America/New_York'), '%H:%i')  AS et_time,
    round(sumIf(toFloat64(volume),
                toDate(toTimeZone(window_start, 'America/New_York')) = '2026-03-20') / 1000, 1) AS settlement_friday_volume_k,
    round(sumIf(toFloat64(volume),
                toDate(toTimeZone(window_start, 'America/New_York')) = '2026-03-13') / 1000, 1) AS ordinary_friday_volume_k
FROM global_markets.delayed_stocks_minute_aggs
WHERE ticker = 'SPY'
  AND window_start >= '2026-03-13 00:00:00'
  AND window_start <  '2026-03-21 00:00:00'
  AND toDate(toTimeZone(window_start, 'America/New_York')) IN ('2026-03-13', '2026-03-20')
  AND (toHour(toTimeZone(window_start, 'America/New_York')) * 60
       + toMinute(toTimeZone(window_start, 'America/New_York'))) BETWEEN 555 AND 600
GROUP BY et_time
ORDER BY et_time

The panel spans 09:15 to 10:00 ET across 46 clock minutes. The 09:30 bucket is the first minute of the regular session, and everything to its left is premarket.

What happens to a position left open into SQ

Nikkei 225 options are European style and cash settled. There is no early exercise and no delivery of shares in any outcome. European style exercise covers what that restriction means day to day.

At settlement the exchange compares the SQ value with the strike. An in the money call is worth the SQ value minus the strike, an in the money put the strike minus the SQ value, and the difference is paid in cash at the contract multiplier of ¥1,000 per index point. An out of the money option settles at zero and leaves the account. The holder takes no action either way.

The part that catches people is the overnight gap. Trading in the contract has already stopped when the settlement price is created, so a strike sitting comfortably out of the money at Thursday's close can finish in the money on Friday's opening composite, and a position that looked safely in the money can settle at nothing. That outcome is ordinary. It follows directly from a settlement rule written around the open. Nikkei 225 options explained covers the contract specifications in full, and 0DTE options from Japan looks at the very short dated end of the same market.

FAQ

When is SQ day for Nikkei 225 options?

SQ day is the second Friday of the contract month, moved earlier to the previous business day when that Friday is an exchange holiday. The expiring contract's last trading day is the business day before, normally the Thursday.

What is the difference between Mega SQ and a normal SQ?

Mega SQ falls in March, June, September and December, when the standard Nikkei 225 futures reach final settlement on the same morning as the options. The other eight months settle options alone and are called minor SQ.

Is the SQ value based on the open or the close?

The open. The SQ value is computed from the opening prices of all 225 index members on SQ morning, so it is fixed before most of the session has traded. The closing price on SQ day plays no part in settlement.

What happens if I hold a Nikkei 225 option through SQ?

The contract is European style and cash settled. An in the money contract is settled automatically against the SQ value at ¥1,000 per index point, and an out of the money contract expires at zero. No shares are delivered and the holder does nothing.

Is SQ day the same as US triple witching?

The quarterly Mega SQ is the closest match. Both fall on a Friday when index futures and index options settle together, and both use an opening composite for the AM settled products. The eight minor SQ days have no single US nickname.

Every panel above ships with the SQL that produced it. To run the same opening auction comparison over a different basket or a different settlement Friday, ask for it in plain English on the Strasmore terminal.