The bigger the one-day surge in VIX's RSI, the more VIX faded afterward. The signal fires at the spike, not before it.
A fast jump in VIX's RSI looks like a momentum trigger. The oscillator lurches higher, volatility is clearly accelerating, and the instinct is to read it as a breakout: get out of the way, a spike is coming. We tested whether that instinct holds. Does a sharp one-day rise in VIX's 14-day RSI actually predict a bigger spike ahead?
We swept the threshold, looking at every day VIX's RSI rose by at least 5, 10, 15, and 20 points in a single session, across 22 years of history. For each, we measured what VIX and the S&P 500 did next and compared it to a plain baseline. The result is not just "no edge." It is the opposite of what the setup promises.
| Condition | Same-day VIX move | VIX peak, next 20d | S&P fell 5%+ |
|---|---|---|---|
| Any day (baseline) | n/a | +23% | 20% |
| RSI jump of 5+ | +11% | +20% | 23% |
| RSI jump of 10+ | +20% | +19% | 26% |
| RSI jump of 15+ | +31% | +16% | 24% |
| RSI jump of 20+ | +46% | +9% | 9% |
Read down the "VIX peak" column. The bigger the RSI jump, the lower the forward spike. A surge of 20 or more is followed by VIX going essentially nowhere, well below the +23% you would get from a random day. The harder the indicator fires, the more it anti-predicts continuation. That is a strange thing for a momentum trigger to do, until you look at one more column.
Look at the same-day move. An RSI jump that size is, by definition, a big VIX up-day that has already happened. A jump of 20 comes on a day VIX rose a median of 46%. You are not catching a precursor to a spike, you are standing in the middle of one. And VIX is strongly mean-reverting: after an outsized single-day surge, the typical path is back down, not further up. The indicator is not early. It is coincident with the very move you hoped it would warn you about, and then it fades.
There is a mild flicker on the equity side, a slightly elevated drawdown rate at the moderate "jump of 10" threshold (26% versus a 20% baseline). But it does not behave like a real signal. It fails to strengthen as the jump grows, and it reverses outright at the extreme, where the largest jumps actually saw fewer 5% drawdowns, on a tiny sample. A relationship that falls apart as you push the dial is noise, not edge.
If there is any consistent pattern here, it points the other way. An outsized RSI surge in VIX is followed by reversion more reliably than continuation. The honest read is to fade the surge, not chase it, which is the opposite of how the indicator is usually traded.
Every single-day RSI surge over 22 years, swept across four thresholds, measured against a plain baseline.
Forward VIX falls as the RSI jump grows, from +20% at a jump of 5 to just +9% at a jump of 20, both at or below the +23% random-day baseline.
A jump that size is a big VIX up-day already, plus 11% to plus 46% on the day itself. The signal marks the move, it does not lead it.
A small drawdown tilt at the middle threshold does not strengthen with bigger jumps and reverses at the extreme. No dose-response means noise.
The one consistent pattern is mean reversion. After an outsized RSI surge, VIX tends to come back down, the opposite of a breakout chase.
Why a fast-firing oscillator on VIX cannot warn you of a VIX spike.
RSI is built from recent price changes, so a big jump in it requires a big move to have already happened. By the time it surges, the event it is "predicting" is the day you are standing in.
When a signal looks dramatic, ask how much of the move is concurrent with the trigger. Here, almost all of it is. The "forward" spike is small precisely because the spike already happened on the signal day.
VIX mean-reverts after an outsized surge, so the usable lean, if any, is to fade the spike rather than chase it. Treat that as an observation, not a strategy: the samples at the extreme thresholds are small.
We test popular signals the honest way: every instance counted, every result measured against a plain baseline. See what else held up, and what did not.
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