A crash-warning indicator: it triggers when an unusual number of NYSE stocks hit both 52-week highs and 52-week lows on the same day while the index is in an uptrend — internal disagreement (“bad breadth”) under a rising surface.
Single triggers fire constantly and are nearly worthless; the standing joke is that the omen has predicted far more crashes than have occurred. Clusters are more interesting: Bluekurtic’s 07/2026 chart counts 9 cluster events since 1970 (≥11 triggers in 3 months) with 100% negative S&P returns three weeks later, median −3.9%. The 2007 and Jan-2018 clusters preceded real drawdowns; 2006 and Sep-2018 were shallow dips and recovery. Honest reading: elevated short-term downside risk on an n=9 sample with a threshold chosen after looking at the data — not a crash call.
The post itself claimed “lower two weeks later, every single time”; its own table showed one positive two-week outcome. See Check the stat against its own chart.
The trigger condition — many 52-week highs and lows at once — is also the signature of a violent leadership rotation, not only of a topping market; see Equity duration.