Effective spread against quoted spread by trade size, AAPL
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 2026-08-07, from Rule 605 vs 606: Execution Quality Reports.
| size_bucket | avg_quoted_spread_bps | avg_effective_spread_bps | eq_over_q_pct |
|---|---|---|---|
| 1 to 99 (odd lot) | 1.19 | 1.1 | 92.5 |
| 100 to 499 | 1.1 | 0.6 | 54.6 |
| 500 to 1,999 | 1.18 | 1.02 | 86.4 |
| 2,000 and up | 1.2 | 1.41 | 117.6 |
- Rows × columns
- 4 × 4
- Computed
- Completeness
- No missing values
- Source
- US exchange, SIP and OPRA market data
- Licence
- Strasmore terms · free, no signup
What each column holds
| Column | Type | Range | Notes |
|---|---|---|---|
size_bucket |
text | 4 distinct values | |
avg_quoted_spread_bps |
number | 1.1 to 1.2 | |
avg_effective_spread_bps |
number | 0.6 to 1.41 | |
eq_over_q_pct |
number | 54.6 to 117.6 | percent |
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
size_bucket,
round(avg(quoted_bps), 2) AS avg_quoted_spread_bps,
round(avg(effective_bps), 2) AS avg_effective_spread_bps,
round(100 * avg(effective_bps) / avg(quoted_bps), 1) AS eq_over_q_pct
FROM
(
SELECT
multiIf(t.size < 100, '1 to 99 (odd lot)',
t.size < 500, '100 to 499',
t.size < 2000, '500 to 1,999',
'2,000 and up') AS size_bucket,
multiIf(t.size < 100, 1, t.size < 500, 2, t.size < 2000, 3, 4) AS bucket_order,
10000 * (q.ask - q.bid) / ((q.ask + q.bid) / 2) AS quoted_bps,
10000 * 2 * abs(t.price - ((q.ask + q.bid) / 2)) / ((q.ask + q.bid) / 2) AS effective_bps
FROM
(
SELECT ticker, sip_timestamp, toFloat64(price) AS price, size
FROM global_markets.stocks_trades
WHERE ticker = 'AAPL'
AND sip_timestamp >= '2026-06-17 14:00:00'
AND sip_timestamp < '2026-06-17 15:00:00'
AND size > 0
AND price > 0
) AS t
ASOF JOIN
(
SELECT ticker, sip_timestamp, toFloat64(bid_price) AS bid, toFloat64(ask_price) AS ask
FROM global_markets.cache_stocks_quotes
WHERE ticker = 'AAPL'
AND sip_timestamp >= '2026-06-17 13:45:00'
AND sip_timestamp < '2026-06-17 15:00:00'
AND bid_price > 0
AND ask_price > bid_price
) AS q
ON t.ticker = q.ticker AND t.sip_timestamp >= q.sip_timestamp
)
WHERE effective_bps < 200 AND quoted_bps < 200
GROUP BY size_bucket, bucket_order
ORDER BY bucket_order
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