What share of MYM's daily trading volume trades after 12:00 PM ET

Methodology

Analysis code was generated by an AI model up to 25 times, run in a sandbox against real MYM 1-minute bars from 2026-03-05 to 2026-09-07, and reviewed automatically. Attempts that computed the same set of measures were grouped, and the figures shown are the median of the largest group. Agreement between attempts lowers the chance of a one-off coding slip; it does not prove the code matches the question, so the exact code is shown below.

bars_et = to_et(bars)
rth = rth_session(bars_et)
rth = rth.copy()
rth['trading_date'] = trading_date(rth)

after_noon = rth.index.time >= pd.Timestamp('12:00').time()

total_vol = rth['volume'].sum()
after_vol = rth.loc[after_noon, 'volume'].sum()

n_days = rth['trading_date'].nunique()

if total_vol > 0 and n_days > 0:
    share = float(after_vol) / float(total_vol)
else:
    share = None

result = {
    'sample_size': int(n_days),
    'share_volume_after_noon_et': share,
    'total_volume': int(total_vol),
    'volume_after_noon': int(after_vol),
}

• Generated by an AI model up to 25 times, run in a sandbox, and reviewed automatically; the figures above are the median of the largest group of attempts that computed the same measures. Agreement between attempts lowers the chance of a one-off coding slip -- it does not prove the code matches the question, so check the definition and code. A one-off calculation, not a permanent fixture.