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Median quoted spread by session window: pre-market vs. regular vs. after-hours, July 8, 2026

Answered against 22 years of US equities and 12 years of US options data and published with the query that produced it. This result is stored as of 2026-07-26, from Market Order vs Limit Order, Measured.

as of ranking 3×4read in context →
Median quoted spread by session window: pre-market vs. regular vs. after-hours, July 8, 2026 — 3 rows by 4 columns, computed from US exchange, SIP and OPRA data.
session_windowspy_spread_centsaapl_spread_centsko_spread_cents
1. Pre-market (4:00-9:30)73228
2. Regular (9:30-16:00)231
3. After-hours (16:00-20:00)62030
Rows × columns
3 × 4
Computed
Completeness
No missing values
Source
US exchange, SIP and OPRA market data
Licence
Strasmore terms · free, no signup
Formats
JSON · CSV · the SQL below

What each column holds

Column definitions for Median quoted spread by session window: pre-market vs. regular vs. after-hours, July 8, 2026, derived from the stored result.
ColumnTypeRangeNotes
session_window text 3 distinct values
spy_spread_cents number 2 to 7
aapl_spread_cents number 3 to 32
ko_spread_cents number 1 to 30

Computed from Strasmore's warehouse of US exchange, SIP and OPRA market data. Equity prices are delayed; options greeks and implied volatility are end-of-day. This result is stored, not recomputed on load — it is exactly the numbers that were returned on , and the query below is what returned them.

the exact SQL behind every number 
SELECT multiIf(et_min < 570, '1. Pre-market (4:00-9:30)', et_min < 960, '2. Regular (9:30-16:00)', '3. After-hours (16:00-20:00)') AS session_window,
       round(quantileDeterministicIf(0.5)(spread_cents, det, ticker = 'SPY'), 1) AS spy_spread_cents,
       round(quantileDeterministicIf(0.5)(spread_cents, det, ticker = 'AAPL'), 1) AS aapl_spread_cents,
       round(quantileDeterministicIf(0.5)(spread_cents, det, ticker = 'KO'), 1) AS ko_spread_cents
FROM (
    SELECT ticker,
           toHour(toTimeZone(sip_timestamp, 'America/New_York')) * 60 + toMinute(toTimeZone(sip_timestamp, 'America/New_York')) AS et_min,
           toFloat64(ask_price - bid_price) * 100 AS spread_cents,
           cityHash64(ticker, sip_timestamp) AS det
    FROM global_markets.cache_stocks_quotes
    WHERE ticker IN ('SPY', 'AAPL', 'KO')
      AND sip_timestamp >= '2026-07-08 04:00:00' AND sip_timestamp < '2026-07-09 04:00:00'
      AND bid_price > 0 AND ask_price > bid_price
)
WHERE et_min >= 240 AND et_min < 1200
GROUP BY session_window
HAVING countIf(ticker = 'SPY') > 0 AND countIf(ticker = 'AAPL') > 0 AND countIf(ticker = 'KO') > 0
ORDER BY session_window

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