The ten worst SPY sessions, 2003–2025: August 8, 2011 is the odd one out
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 The 2011 US Downgrade: Black Monday's Tape.
| session | change_pct | downgrade_rank | top10_outside_crises | two_week_slide_pct |
|---|---|---|---|---|
| 2020-03-16 | -11.6 | 9 | 1 | -10.8 |
| 2020-03-12 | -9.6 | 9 | 1 | -10.8 |
| 2008-10-15 | -9.2 | 9 | 1 | -10.8 |
| 2008-12-01 | -8.9 | 9 | 1 | -10.8 |
| 2020-03-09 | -7.7 | 9 | 1 | -10.8 |
| 2008-09-29 | -7 | 9 | 1 | -10.8 |
| 2008-10-09 | -6.8 | 9 | 1 | -10.8 |
| 2008-11-20 | -6.6 | 9 | 1 | -10.8 |
| 2011-08-08 | -6.5 | 9 | 1 | -10.8 |
| 2008-10-07 | -6.1 | 9 | 1 | -10.8 |
- Rows × columns
- 10 × 5
- Period covered
- to
- 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 |
|---|---|---|---|
session |
date | 2008-09-29 to 2020-03-16 | |
change_pct |
number | -11.6 to -6.1 | percent |
downgrade_rank |
number | every row is 9 | |
top10_outside_crises |
number | every row is 1 | |
two_week_slide_pct |
number | every row is -10.8 | 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
WITH daily AS (
SELECT
toDate(toTimeZone(window_start, 'America/New_York')) AS et_date,
argMax(toFloat64(close), window_start) AS close_usd
FROM global_markets.delayed_stocks_minute_aggs
WHERE ticker = 'SPY'
AND (toHour(toTimeZone(window_start, 'America/New_York')) * 60 + toMinute(toTimeZone(window_start, 'America/New_York'))) BETWEEN 570 AND 959
AND window_start >= toDateTime('2003-01-01 00:00:00') AND window_start < toDateTime('2026-01-01 00:00:00')
GROUP BY et_date
),
changes AS (
SELECT et_date, close_usd,
lagInFrame(close_usd) OVER (ORDER BY et_date ASC ROWS BETWEEN 1 PRECEDING AND CURRENT ROW) AS prev_close
FROM daily
),
ranked AS (
SELECT et_date, close_usd,
round((close_usd / prev_close - 1) * 100, 1) AS change_pct,
row_number() OVER (ORDER BY close_usd / prev_close ASC, et_date ASC) AS day_rank
FROM changes
WHERE prev_close > 0
),
enriched AS (
SELECT et_date, change_pct, day_rank,
max(if(et_date = toDate('2011-08-08'), day_rank, 0)) OVER () AS downgrade_rank,
sum(if(day_rank <= 10 AND toYear(et_date) NOT IN (2008, 2020), 1, 0)) OVER () AS top10_outside_crises,
round((max(if(et_date = toDate('2011-08-05'), close_usd, 0)) OVER () / max(if(et_date = toDate('2011-07-22'), close_usd, 0)) OVER () - 1) * 100, 1) AS two_week_slide_pct
FROM ranked
)
SELECT
toString(et_date) AS session,
change_pct,
downgrade_rank,
top10_outside_crises,
two_week_slide_pct
FROM enriched
WHERE day_rank <= 10
ORDER BY day_rank
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