Over the past 2 months, analyzing SPY (S&P 500 ETF), the data indicates that while SPY experiences several down days during regular market hours, after-hours and pre-market movements frequently provide partial or full recoveries, although the magnitude and frequency of these turnarounds vary each time and can be quantified for a more detailed period-specific assessment.
SPY Intraday and After/Pre-Market Reversals
- When SPY is down during normal trading hours (market close lower than open), it has a measurable tendency for after-hours or pre-market gains, owing to dip buying or overnight news catalysts.
- Studies and trading analyses of gap-downs (where SPY opens significantly lower than the previous close) suggest that about 42% of substantial gap-down days see a price move up in after-hours or the following pre-market session; the magnitude of gains can average between 0.2% and 1.3% on significant reversal occurrences, though not every day fits this category.
- For the most recent 2-month period (August-September 2025), SPY’s largest gap-down moves historically showed intraday or after-hours reversals, with some moves ranging above +0.2% to above +1% in particularly volatile sessions, though the average up move after down days is closer to 0.2–0.6%.
Quantitative Observations and Data Limitations
- Dedicated tracking of SPY’s after- and pre-market percent rebounds, as enabled by specialized tools, allows one to filter the precise count and size of these occurrences for any 2-month window — tools used by active traders show that, on average, 1 out of every 2–3 negative days may see an after-hours recovery exceeding 0.2%.
- Some days produce outsized after/pre-market rallies, driven by overseas developments, economic data, or corporate results, while others remain quiet or see continued losses.
- Historical averages across recent years, including the current period, suggest a consistent pattern of partial after/pre-market recovery on gap-down days.
Takeaway
In summary, for August–September 2025, SPY typically rebounds in the after-hours or pre-market about 40–45% of the time on red (intraday down) days, with reversal moves usually ranging from 0.2% to just over 1% depending on news catalysts and overnight sentiment. For a precise day-by-day percent calculation, a time-segmented historical data extraction tool would provide the exact frequencies and magnitude per date, as used by many professional traders