The Cboe Volatility Index closed at 17.84 on September 10, its highest level in six weeks and the fourth consecutive weekly gain. The climb has tracked the escalation between Washington and Tehran over tanker traffic through the Strait of Hormuz, where shipping analytics firm Kpler has documented daily transits falling from roughly 20 vessels before the conflict to a ten day average near 13.
WTI crude has moved from the low 90s in early August to above 97 dollars a barrel by September 10, and gold has held near 4,400 dollars an ounce despite a stronger U.S. dollar, a combination that typically signals genuine investor unease rather than a single headline shock.
A Four-Week Climb Markets Have Mostly Shrugged Off
The size of the move is not unusual. A VIX reading of 17.84 remains well below the 20 level markets generally treat as the threshold for elevated volatility, and far below the readings seen during acute market stress. The shape of the climb is what deserves attention: four consecutive weekly increases, each smaller than the underlying headlines would suggest, layered on top of a widening supply disruption that has now drawn direct U.S. strikes on Iranian tankers.
The index climb from a mid-August low near 14.3 to 17.84 by September 10 traces closely onto the Hormuz escalation timeline, with the steepest single-day jump arriving the day after U.S. forces struck Iranian tankers for the first time.
The VIX has climbed for four straight weeks to 17.84, still below the 20 level widely treated as the threshold for elevated volatility. Source: Cboe Global Markets.
The AAII sentiment survey published September 9 puts bearish investors at 39.3 per cent against 38.0 per cent bullish, a gap that has narrowed and widened from week to week without settling in either direction since late July. That is not the profile of a market that has made up its mind.
Why the Absence of Panic Is Itself the Signal
Work by Daniel Kahneman and Amos Tversky, published in 1979, established that investors feel the pain of a loss roughly twice as intensely as the pleasure of an equivalent gain. That effect does not always surface as visible panic. It often appears first as a quiet reluctance to look: a client who stops checking statements and stops asking questions at precisely the moment the questions matter most.
A four-week grind higher in volatility, with no single dramatic down day to force a conversation, is exactly the environment where that reluctance takes hold. Clients are not calling because nothing has happened to them yet, not because nothing is happening in the market.
A Recency Effect Working in the Wrong Direction
Recency bias, the tendency to weight the most recent data most heavily, has spent most of 2026 working in favour of calm. A quiet summer taught investors that headlines about tanker seizures and missile strikes do not necessarily translate into portfolio damage, and that lesson has been reinforced every week the market failed to fall sharply. The same mechanism that built this complacency during a quiet stretch can unwind just as fast once a single sharp move breaks the pattern investors have come to expect.
Research on mental accounting by Richard Thaler suggests investors who have filed the Hormuz conflict away as background noise will treat the next escalation as a far larger surprise than an investor who has been tracking the volatility trend all along. The four week climb in the VIX is the kind of data that belongs in front of a client now, while the conversation is still calm.