Backtested and hypothetical results, shown for educational purposes only — not investment advice. Past performance does not indicate future results.

Mean Reversion

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US indices SPY QQQ IWM DIA International FXI EEM
IONS’s daily moves don’t reliably mean-revert. The dip-buy stats below are weak or noisy — at the daily close-to-close horizon this signal works cleanly on the broad equity indices (SPY, QQQ) and mostly breaks down on commodities and crypto.
Expected return · next day

IONS — Stretched, weak edge$54.21 · 2026-09-11

IONS shows only a faint, unreliable daily reversal bias.

Current stretch: RSI(2) at 1 is deep oversold, 6 down days in a row — but the daily edge here is thin.

Today
-2.6%
last close-to-close
RSI(2)
1.1
oversold
vs 50-day avg
-8.6%
-0.6σ
Streak
6 down
closes in a row
Off 20-day high
-15.6%
pullback depth
Reversal character: after an up day, next day averages +0.01% (45% up); after a down day, +0.19% (49% up). Reversal score +0.18%, 1-day autocorrelation -0.03 — negative = mean-reverting.
Growth of $1, close-to-close, since 1991. The two lines are held the day after their trigger and sit in cash otherwise, so they trade a similar number of days — the comparison is the dip-buy leg (green) against its opposite (red), not against buy & hold. No costs or slippage.
Forward return by RSI(2) at the close (toggle mean / median above). Low RSI(2) = short-term oversold. Bar outlined = where IONS is now.
Forward return by how far price sits from its 50-day average (in standard deviations). Outlined = now.
The next-day return after a run of consecutive up or down closes. A rising staircase toward the “down” end is mean reversion.
Mean-reversion edge by year — the dip-buy leg's next-day return minus its opposite (after a down day vs after an up day, or bottom- vs top-decile RSI(2)). Above zero = the name faded moves that year. Bars are the mean, which a crash can swing hard in either direction (2020); the tick marks are the median — the typical day.
Matched-exposure comparisons — each pair trades a similar number of days, so raw returns are comparable. RSI(2) deciles use thresholds ≤7.4 and ≥93.0.
RuleDays heldAvg / dayWin rate TotalCAGRSharpeMax DD
■ After a DOWN close 4,276 (48%) +0.194% 49.2% +22,843% +16.6% 0.58 -78.7%
■ After an UP close 4,150 (47%) +0.015% 44.9% -95% -8.2% 0.04 -99.1%
■ Bottom 10% RSI(2) 891 (10%) +0.389% 49.4% +1,462% +8.1% 0.48 -46.0%
■ Top 10% RSI(2) 890 (10%) +0.178% 46.0% +102% +2.0% 0.20 -68.0%
How to read this  ▾

Some assets mean-revert at short horizons (a sharp move tends to partly reverse); others trend (a move tends to continue). At the daily close-to-close horizon the reversal shows up cleanly and consistently in the broad equity indices and mostly breaks down elsewhere — commodities, crypto, and individual stocks carry their own momentum. The names above are the ones where it holds up.

RSI(2) is a 2-day momentum oscillator — below ~10 is short-term oversold, above ~90 overbought. Distance from the 50-day average is measured in standard deviations (z-score). Streak counts consecutive up or down closes. For each, we show what happened over the next 1–5 days, historically.

The strategy table pairs each dip-buy rule against its opposite — day-after-a-down-close vs day-after-an-up-close, and the bottom vs top RSI(2) decile. Both legs of a pair are held one day and trade a similar number of days, so raw returns compare fairly (unlike buy & hold, which wins on total return simply by always being invested). Avg / day — mean return on the days the rule is in the market — is the cleanest apples-to-apples number. Frictionless: no commissions or slippage. A character test, not a tradeable system. Past behaviour is not a forecast.

End-of-day adjusted closes, refreshed nightly. 8,893 trading days, 1991-05-17 – 2026-09-11. Backward-looking statistics, not investment advice.