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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.

as of series 10×5read in context →
The ten worst SPY sessions, 2003–2025: August 8, 2011 is the odd one out — 10 rows by 5 columns, computed from US exchange, SIP and OPRA data.
sessionchange_pctdowngrade_ranktop10_outside_crisestwo_week_slide_pct
2020-03-16-11.691-10.8
2020-03-12-9.691-10.8
2008-10-15-9.291-10.8
2008-12-01-8.991-10.8
2020-03-09-7.791-10.8
2008-09-29-791-10.8
2008-10-09-6.891-10.8
2008-11-20-6.691-10.8
2011-08-08-6.591-10.8
2008-10-07-6.191-10.8
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
Formats
JSON · CSV · the SQL below

What each column holds

Column definitions for The ten worst SPY sessions, 2003–2025: August 8, 2011 is the odd one out, derived from the stored result.
ColumnTypeRangeNotes
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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More from this analysisThe 2011 US Downgrade: Black Monday's Tape
SPY by half-hour: August 8, 2011 regular session series 13×4 Treasury yields through the downgrade window, August 1–15, 2011 series 11×5 SPY closes, August 8-12, 2011: crash, rip, crash, rip series 5×4 August 8, 2011 across the tape: banks, staples, gold, and the fear gauge ranking 9×4 The recovery, dated: reclaim, failed hold, true bottom, and the last close below scalar 1×9 SPY on August 8, 2011: the downgrade Monday, receipted scalar 1×11 See all 2,170 queries →