Is the Market a Random Walk? Real Returns
Deepest fall: 400 matched random walks versus SPYranking ·
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Excess kurtosis by year, against the full window levelranking ·
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Bootstrapping Backtest Confidence Bands
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One position, one year at a time: SPY annualized Sharpe by calendar yeartable ·
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Measured Sharpe dispersion across non-overlapping SPY windows, 2006 to 2025table ·
2026-08-14 · 5×6
Lag-one autocorrelation: signed returns against absolute returns, 2016 to 2025ranking ·
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Pairs Trading and Cointegration Explained
Weekly z score of the KO/PEP spread, hedge ratio fitted on 2023 onlyseries ·
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Where the KO/PEP spread sat twenty sessions later, by starting z score (2019-2025)ranking ·
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Daily-return correlation vs price-level correlation, five familiar pairs (2024-2025)ranking ·
2026-08-13 · 5×3
Hedge ratio refitted each calendar year, two sector pairsranking ·
2026-08-13 · 7×3
Deepest fall: 400 matched random walks versus SPY
Deepest fall: 400 matched random walks versus SPY
| percentile | sim_drawdown_depth_pct | spy_drawdown_depth_pct | paths_at_least_as_deep_pct |
|---|---|---|---|
| p05 | 31.8 | 56.5 | 14 |
| p25 | 37.9 | 56.5 | 14 |
| p50 | 45 | 56.5 | 14 |
| p75 | 51.5 | 56.5 | 14 |
| p95 | 63.3 | 56.5 | 14 |
the exact SQL behind every number
WITH daily AS (SELECT date, argMax(toFloat64(close), _ingest_time) AS px FROM global_markets.stocks_daily_aggs WHERE ticker = 'SPY' AND date >= '2006-01-01' AND date <= '2026-09-30' GROUP BY date),
rets AS (SELECT date, px / prev_px - 1 AS ret FROM (SELECT date, px, lagInFrame(px) OVER (ORDER BY date ROWS BETWEEN 1 PRECEDING AND CURRENT ROW) AS prev_px FROM daily) WHERE prev_px > 0),
stats AS (SELECT avg(ret) AS mu, stddevPop(ret) AS sd, count() AS n FROM rets),
real_curve AS (SELECT date, sum(log(1 + ret)) OVER (ORDER BY date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS log_equity FROM rets),
real_depth AS (SELECT 100 * (1 - exp(min(log_equity - greatest(peak, 0.0)))) AS depth_pct FROM (SELECT log_equity, max(log_equity) OVER (ORDER BY date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS peak FROM real_curve)),
steps AS (SELECT pp.p AS path_id, arrayJoin(range(toUInt32(s.n))) AS t, s.mu AS mu, s.sd AS sd FROM stats AS s CROSS JOIN (SELECT arrayJoin(range(400)) AS p) AS pp),
draws AS (SELECT path_id, t, mu + sd * sqrt(-2 * log((cityHash64('strasmore-walk', path_id, t) % 1000000 + 0.5) / 1000000)) * cos(2 * pi() * ((cityHash64('strasmore-phase', t, path_id) % 1000000 + 0.5) / 1000000)) AS ret FROM steps),
sim_curve AS (SELECT path_id, t, sum(log(1 + ret)) OVER (PARTITION BY path_id ORDER BY t ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS log_equity FROM draws),
sim_depth AS (SELECT path_id, 100 * (1 - exp(min(log_equity - greatest(peak, 0.0)))) AS depth_pct FROM (SELECT path_id, log_equity, max(log_equity) OVER (PARTITION BY path_id ORDER BY t ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS peak FROM sim_curve) GROUP BY path_id),
summary AS (SELECT quantilesDeterministic(0.05, 0.25, 0.5, 0.75, 0.95)(d.depth_pct, d.path_id) AS qs, round(any(r.depth_pct), 1) AS spy_depth, round(100 * countIf(d.depth_pct >= r.depth_pct) / count(), 1) AS deeper_share FROM sim_depth AS d CROSS JOIN real_depth AS r)
SELECT
tupleElement(tagged, 1) AS percentile,
round(tupleElement(tagged, 2), 1) AS sim_drawdown_depth_pct,
spy_depth AS spy_drawdown_depth_pct,
deeper_share AS paths_at_least_as_deep_pct
FROM (SELECT arrayJoin(arrayZip(['p05', 'p25', 'p50', 'p75', 'p95'], qs)) AS tagged, spy_depth, deeper_share FROM summary)
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