STRASMORE/EXPLORE 2,170 QUERIES

Whole-tape census: locked, crossed, and one-sided records across every NBBO update of the session

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 2026-08-22, from Locked and Crossed Markets, Explained With Data.

as of scalar 1×7read in context →
session date
2026-08-18
updates m
406
locked m
7.41
crossed k
43.8
locked per crossed
169
locked or crossed per 10k
183.4
one sided per 10k
3.2
Rows × columns
1 × 7
Period covered
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 Whole-tape census: locked, crossed, and one-sided records across every NBBO update of the session, derived from the stored result.
ColumnTypeRangeNotes
session_date date 2026-08-18
updates_m number every row is 406
locked_m number every row is 7.41
crossed_k number every row is 43.8
locked_per_crossed number every row is 169
locked_or_crossed_per_10k number every row is 183.4
one_sided_per_10k number every row is 3.2

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 
WITH (
    SELECT max(toDate(toTimeZone(window_start, 'America/New_York')))
    FROM global_markets.delayed_stocks_minute_aggs
    WHERE ticker = 'SPY' AND window_start < toDateTime(today() - 3)
) AS census_day
SELECT
    formatDateTime(census_day, '%Y-%m-%d') AS session_date,
    round(count() / 1e6, 0) AS updates_m,
    round(countIf(bid_price = ask_price AND bid_price > 0) / 1e6, 2) AS locked_m,
    round(countIf(bid_price > ask_price AND ask_price > 0) / 1e3, 1) AS crossed_k,
    round(countIf(bid_price = ask_price AND bid_price > 0) / toFloat64(greatest(countIf(bid_price > ask_price AND ask_price > 0), 1)), 0) AS locked_per_crossed,
    round(countIf(bid_price >= ask_price AND ask_price > 0 AND bid_price > 0) / toFloat64(count()) * 1e4, 1) AS locked_or_crossed_per_10k,
    round(countIf(bid_price <= 0 OR ask_price <= 0) / toFloat64(count()) * 1e4, 1) AS one_sided_per_10k
FROM global_markets.cache_stocks_quotes
WHERE sip_timestamp >= toDateTime(census_day)
  AND sip_timestamp < toDateTime(census_day + 1)

Run your own version of this

The same 22 years of US equities and 12 years of options data are queryable in SQL or plain English. A free account runs 100 queries a day and takes no card.

More from this analysisLocked and Crossed Markets, Explained With Data
The receipts: locked vs crossed totals, and the rate by session stretch (premarket, open, noon, close, ET) scalar 1×10 → Locked-or-crossed records per 10,000 updates by 30-minute ET bucket, checked set, extended hours included series 32×3 → The census by name: eight liquid tickers and two thin small caps, recent completed sessions table 10×7 → AAPL: the last recorded NBBO quote in our data window scalar 1×7 → AAPL: average NBBO updates per minute by half-hour bucket (ET, 4 a.m. to 8 p.m.) series 32×3 → AAPL median quoted spread by 30-minute bucket (ET, extended hours included) series 32×2 → See all 2,170 queries →