The stock market is behaving strangely. On July 30th, Microsoft’s market value jumped by $450 billion (€386 billion). The following day, Amazon added $388 billion while Apple lost $360 billion.
These were extraordinary moves, but they did not translate into anything like comparable volatility in the overall market.
This is known as dispersion: the extent to which individual stocks move differently from one another.
The latest note from Acadian Asset Management’s Owen Lamont, a researcher who has studied the dynamics of the dotcom bubble, notes daily dispersion on July 30th was the third-highest since 2015, beaten only by November 9th, 2020, (“vaccine Monday”) and January 27th, 2025, (Wall Street’s DeepSeek shock).
It is not an isolated reading. In June, Bank of America (BofA) noted the gap between the best and worst performing technology stocks reached 120 percentage points, the widest since February 2000.
More recently, a measure of single-stock volatility based on options-market readings rose above 50 in July, the highest reading since April 2025’s US tariffs shock.
However, the Vix, which measures volatility at the index level, barely moved. Both BofA and Lamont note that combination – wild volatility in individual stocks but relative calm in the index – is reminiscent of the late 1990s.
However, we also witnessed high dispersion during the global financial crisis and the pandemic, Lamont says. If artificial intelligence is transforming companies’ prospects, huge differences in share prices may simply reflect uncertainty and rational reassessment.
One thing for sure, he says, is that portfolios “should be designed to handle extreme price volatility”.
The message: buckle up.
