The folklore is directionally true, but the naive fade is not a strong trading strategy.
This submission tests the old trading saying with a strict range-gap definition on U.S. equities, then separates the empirical question from the trading question. The short version: prices often do revisit yesterday's range, but that does not automatically create a good next-day fade.
The Definition
A strict gap up means today's low is above yesterday's high. A strict gap down means today's high is below yesterday's low. The gap is considered filled once a later trading day trades back through the prior day's extreme.
The trade test is deliberately simple: fade the gap at the next open, target the fill level, stop out at a fixed percentage from the gap day's close, and abandon the trade after a fixed number of days.
{
"universe": "sp500",
"tickers": null,
"start_date": "2016-04-19",
"end_date": "2026-04-19",
"gap": {
"direction": "both",
"min_gap_pct": 0.01,
"fill_horizons": [
1,
5,
20,
60
]
},
"trade": {
"position_size_usd": 10000.0,
"stop_loss_pct": 0.03,
"time_stop_days": 20,
"commission_bps": 1.0,
"slippage_bps": 2.0
}
}
What The Data Says
The claim gets stronger as the holding horizon expands. That matters, because folklore usually speaks in eventual terms, while a tradable setup has to care about timing.
The Trade Test
This is the more useful question for a trader: if you actually fade the gap instead of just counting later fills, do the profits justify the path risk, capital lock-up, and tail events?
Why The Story Breaks
A high eventual fill rate is not the same thing as a high-quality trade. These three frictions explain most of the gap between those claims.
Small edge, large stop
The median strict gap is only 1.8% while the stop is fixed at 3.0%. That is only 0.61x reward-to-risk before slippage.
Fills are often too slow
Among gaps that do fill, 35.8% take longer than the 20-day time stop. The folklore can be directionally right and still arrive too late for this trade design.
Tail losses dominate
Stops account for 58.6% of exits and the worst realized trade loses 36.2%.
Worst Trades
The losers below are the trades that keep a superficially high win-rate story from turning into a durable edge.
| Symbol | Side | Entry | Exit | Reason | Return |
|---|---|---|---|---|---|
| BLDR | long | 2020-03-13 | 2020-03-16 | stop | -36.22% |
| NCLH | long | 2020-03-13 | 2020-03-18 | stop | -29.84% |
| TDG | long | 2020-03-13 | 2020-03-16 | stop | -23.97% |
| ROP | long | 2020-03-13 | 2020-03-16 | stop | -22.08% |
| OXY | long | 2020-03-10 | 2020-03-11 | stop | -21.26% |
| RCL | long | 2020-03-13 | 2020-03-13 | stop | -20.72% |
| MPC | long | 2020-03-13 | 2020-03-16 | stop | -20.65% |
| TRGP | long | 2020-03-10 | 2020-03-10 | stop | -20.52% |