株式併合とは？良いか悪いか

SELECT
    countIf(adjustment_type = 'reverse_split') AS reverse_splits,
    countIf(adjustment_type = 'forward_split') AS forward_splits,
    round(100.0 * countIf(adjustment_type = 'reverse_split')
        / greatest(countIf(adjustment_type IN ('reverse_split', 'forward_split')), 1), 1) AS reverse_pct_of_splits
FROM global_markets.stocks_splits
WHERE toYear(execution_date) = 2026
  AND execution_date <= today()

SELECT
    toYear(execution_date) AS year,
    countIf(adjustment_type = 'reverse_split') AS reverse_splits,
    countIf(adjustment_type = 'forward_split') AS forward_splits,
    round(countIf(adjustment_type = 'reverse_split')
        / greatest(countIf(adjustment_type = 'forward_split'), 1), 1) AS reverse_per_forward
FROM global_markets.stocks_splits
WHERE execution_date >= '2019-01-01'
  AND execution_date <= today()
GROUP BY year
ORDER BY year

SELECT
    concat('1-for-', toString(split_from)) AS ratio,
    count() AS reverse_splits
FROM global_markets.stocks_splits
WHERE adjustment_type = 'reverse_split'
  AND toYear(execution_date) = 2026
  AND execution_date <= today()
  AND split_to = 1
GROUP BY split_from
ORDER BY count() DESC, split_from ASC
LIMIT 10

SELECT
    execution_date,
    ticker,
    concat(toString(split_to), '-for-', toString(split_from)) AS ratio,
    round(split_from / split_to, 2) AS old_shares_per_new
FROM global_markets.stocks_splits
WHERE adjustment_type = 'reverse_split'
  AND execution_date <= today()
  AND split_from > split_to
  AND ticker != 'SPCX'
ORDER BY execution_date DESC, split_from / split_to DESC, ticker ASC
LIMIT 12

WITH cohort AS (
    SELECT ticker, min(execution_date) AS ex
    FROM global_markets.stocks_splits
    WHERE adjustment_type = 'reverse_split'
      AND execution_date >= today() - INTERVAL 270 DAY
      AND execution_date <= today() - INTERVAL 120 DAY
      AND ticker != 'SPCX'
    GROUP BY ticker
),
bars AS (
    SELECT ticker,
           toDate(toTimeZone(window_start, 'America/New_York')) AS d,
           toFloat64(argMax(close, window_start)) AS px
    FROM global_markets.delayed_stocks_minute_aggs
    WHERE (ticker IN (SELECT ticker FROM cohort) OR ticker = 'SPY')
      AND window_start >= today() - INTERVAL 275 DAY
      AND (toHour(toTimeZone(window_start, 'America/New_York')) * 60
           + toMinute(toTimeZone(window_start, 'America/New_York'))) BETWEEN 570 AND 959
    GROUP BY ticker, d
),
series AS (
    SELECT ticker,
           arrayMap(x -> x.1, arraySort(x -> x.1, groupArray((d, px)))) AS days,
           arrayMap(x -> x.2, arraySort(x -> x.1, groupArray((d, px)))) AS prices
    FROM bars
    GROUP BY ticker
),
spy AS (
    SELECT days AS spy_days, prices AS spy_prices
    FROM series
    WHERE ticker = 'SPY'
),
horizons AS (SELECT arrayJoin([5, 21, 63]) AS h),
fwd AS (
    SELECT c.ticker AS ticker,
           h.h AS h,
           indexOf(s.days, c.ex) AS i0,
           indexOf(spy.spy_days, c.ex) AS j0,
           (s.prices[i0 + h.h] / s.prices[i0] - 1) * 100 AS ret,
           (spy.spy_prices[j0 + h.h] / spy.spy_prices[j0] - 1) * 100 AS spy_ret
    FROM cohort AS c
    INNER JOIN series AS s ON s.ticker = c.ticker
    CROSS JOIN horizons AS h
    CROSS JOIN spy AS spy
    WHERE i0 > 0
      AND j0 > 0
      AND length(s.prices) >= i0 + h.h
      AND s.prices[i0] > 0
)
SELECT multiIf(h = 5, '1 week after (5 sessions)',
               h = 21, '1 month after (21 sessions)',
               '3 months after (63 sessions)') AS horizon,
       count() AS splits_measured,
       round(quantileDeterministic(0.5)(ret, cityHash64(ticker)), 1) AS median_stock_pct,
       round(abs(quantileDeterministic(0.5)(ret, cityHash64(ticker))), 1) AS median_stock_pct_abs,
       round(quantileDeterministic(0.5)(spy_ret, cityHash64(ticker)), 1) AS median_spy_pct,
       round(quantileDeterministic(0.5)(ret, cityHash64(ticker))
             - quantileDeterministic(0.5)(spy_ret, cityHash64(ticker)), 1) AS median_gap_pct,
       round(100.0 * countIf(ret < 0) / count(), 1) AS pct_below_split_day
FROM fwd
GROUP BY h
ORDER BY h

WITH cohort AS (
    SELECT ticker, min(execution_date) AS ex
    FROM global_markets.stocks_splits
    WHERE adjustment_type = 'reverse_split'
      AND execution_date >= today() - INTERVAL 540 DAY
      AND execution_date <= today() - INTERVAL 365 DAY
      AND ticker != 'SPCX'
    GROUP BY ticker
),
repeats AS (
    SELECT c.ticker AS ticker, count() AS later_reverse_splits
    FROM cohort AS c
    INNER JOIN global_markets.stocks_splits AS s ON s.ticker = c.ticker
    WHERE s.adjustment_type = 'reverse_split'
      AND s.execution_date > c.ex
      AND s.execution_date <= c.ex + INTERVAL 365 DAY
    GROUP BY c.ticker
),
bars AS (
    SELECT ticker, toDate(toTimeZone(window_start, 'America/New_York')) AS d
    FROM global_markets.delayed_stocks_minute_aggs
    WHERE ticker IN (SELECT ticker FROM cohort)
      AND (
            (window_start >= today() - INTERVAL 545 DAY AND window_start < today() - INTERVAL 360 DAY)
            OR window_start >= today() - INTERVAL 45 DAY
          )
      AND (toHour(toTimeZone(window_start, 'America/New_York')) * 60
           + toMinute(toTimeZone(window_start, 'America/New_York'))) BETWEEN 570 AND 959
    GROUP BY ticker, d
),
status AS (
    SELECT c.ticker AS ticker,
           countIf(b.d < c.ex) AS pre_split_days,
           countIf(b.d >= today() - 45) AS recent_days,
           any(ifNull(r.later_reverse_splits, 0)) AS later_reverse
    FROM cohort AS c
    INNER JOIN bars AS b ON b.ticker = c.ticker
    LEFT JOIN repeats AS r ON r.ticker = c.ticker
    GROUP BY c.ticker
    HAVING pre_split_days > 0
)
SELECT multiIf(recent_days = 0, 'Stopped printing trades',
               later_reverse > 0, 'Still trading, split again in reverse',
               'Still trading, no second reverse split') AS outcome_one_year_on,
       count() AS companies,
       round(100.0 * count() / sum(count()) OVER (), 1) AS pct_of_cohort
FROM status
GROUP BY outcome_one_year_on
ORDER BY indexOf(['Still trading, no second reverse split',
                  'Still trading, split again in reverse',
                  'Stopped printing trades'], outcome_one_year_on)

SELECT
    execution_date,
    concat(toString(split_to), '-for-', toString(split_from)) AS ratio,
    concat(monthName(execution_date), ' ', toString(toYear(execution_date))) AS month_label,
    concat(monthName(execution_date), ' ', toString(toDayOfMonth(execution_date)), ', ',
           toString(toYear(execution_date))) AS date_label,
    split_from,
    split_to
FROM global_markets.stocks_splits
WHERE ticker = 'ASST'
  AND adjustment_type = 'reverse_split'
ORDER BY execution_date

SELECT
    toDate(toTimeZone(window_start, 'America/New_York')) AS date,
    concat(monthName(date), ' ', toString(toDayOfMonth(date)), ', ', toString(toYear(date))) AS date_label,
    round(toFloat64(argMax(close, window_start)), 2) AS close
FROM global_markets.delayed_stocks_minute_aggs
WHERE ticker = 'ASST'
  AND window_start >= toDateTime('2026-01-30 00:00:00')
  AND window_start < toDateTime('2026-05-09 00:00:00')
  AND (toHour(toTimeZone(window_start, 'America/New_York')) * 60
       + toMinute(toTimeZone(window_start, 'America/New_York'))) BETWEEN 570 AND 959
GROUP BY date
ORDER BY date