SPY's median quoted spread by half hour, 4:00 am to 8:00 pm ET

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 Microstructure Deep-Dive: June 29, 2026.

Rows × columns

32 × 3

Period covered

04:00 to 19:30

Computed

2026-07-26

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

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 2026-07-26, and the query below is what returned them.

SELECT
    formatDateTime(toTimeZone(toStartOfInterval(sip_timestamp, INTERVAL 30 MINUTE), 'America/New_York'), '%H:%i') AS et_time,
    round(quantileExactIf(0.5)(toFloat64(ask_price - bid_price), bid_price > 0 AND ask_price >= bid_price) * 100, 1) AS median_spread_cents,
    count() AS quote_updates
FROM global_markets.cache_stocks_quotes
WHERE ticker = 'SPY' AND sip_timestamp >= '2026-06-29 08:00:00' AND sip_timestamp < '2026-06-30 00:00:00'
GROUP BY et_time
ORDER BY et_time