Bull market's volume tell: what a surge in trading activity is signalling about the cycle
A sharp pickup in US stock trading volume is the kind of tell that historically marks the later innings of a bull market. The reading is contested — and so is what to do about it.
US equity trading volume has climbed sharply in recent sessions, the kind of acceleration that veterans of past cycles watch for what it implies about where the bull market stands. On 22 June 2026, Melissa Brown, managing director of investment decision research at SimCorp, said the surge in turnover could indicate that the current advance is entering its later stages. The remark, delivered to Reuters, lands at a moment when indices have already pushed through a series of records and the underlying economy is sending mixed signals on growth and inflation.
Volume is the unglamorous half of any market story. Prices get the headlines; the number of shares changing hands tells you who is showing up. A late-cycle volume spike, in the textbook version, is what happens when the marginal buyer shifts from long-only institutions and retail accumulators to fast-money traders hedging, rotating, and positioning for a turn. The same tape that prints new highs can carry the fingerprints of a crowd preparing to exit.
What the volume barometer is reading
Brown's argument is not that the market is about to crash. It is that the character of demand is changing. Rising volume alongside rising prices is consistent with conviction buying. Rising volume alongside choppier price action, or a narrowing of leadership into a handful of mega-cap names, is consistent with a maturing cycle. Brown told Reuters that the recent pattern fits the latter profile more than the former, which is why she flagged it as a possible late-stage signal.
The mechanics matter. In the early and middle innings of a bull market, breadth is wide: a broad cross-section of sectors participates, corporate buybacks absorb supply quietly, and retail flows add a slow, accumulating bid. As the cycle ages, that mix gives way to concentration, with the index carried by a smaller set of names whose earnings are tied to AI capex, energy infrastructure, or a narrow set of consumer franchises. Volume spikes in that environment often accompany rotation, not fresh enthusiasm, and they tend to precede volatility expansions.
Why this is not a 1999 or 2021 replay
The reflexive read is to compare every late-cycle signature to either the dot-com blow-off or the meme-stock frenzy of 2020–21. Both analogies are imperfect. The current cycle has been unusually narrow and unusually driven by a single technological narrative — the build-out of AI infrastructure and the equity premium attached to it. That is closer in flavour to 1999 than to 2021, but the macro backdrop is different: a Federal Reserve that has begun to ease after a tightening cycle, a labour market that is cooling rather than overheating, and earnings growth that is positive but concentrated.
There is also a structural difference in who is on the other side of the trade. In prior late-cycle episodes, the marginal seller was often a corporate buyer stepping back as buyback windows narrowed. Today, the same dynamic is present, but it is overlaid with a new category of flow: systematic and factor-based strategies that rebalance mechanically and amplify the speed of rotation. A volume spike in that environment can be self-reinforcing, with algorithms reacting to the very signals they create.
The counter-read
Not every volume surge is a topping signal. A second reading, common among the more bullish desks, holds that rising volume in an uptrend is simply evidence of healthy participation — that a market advancing on thin volume is more fragile than one advancing on heavy turnover. Bullish strategists also point to the composition of the demand: corporate buybacks remain a structural bid, passive flows continue to absorb new issuance, and household balance sheets have rebuilt equity exposure only gradually since the 2022 trough.
The bullish case does not deny that the cycle is maturing. It argues that "later stages" and "imminent end" are not the same thing, and that the historical record of mistaking late-stage bull markets for exhausted ones is long. A market can spend months, sometimes years, churning at the top before rolling over — and the time spent churning is precisely when broad index returns stagnate and stock-picking dispersion widens.
What it means for positioning
The practical question is what a portfolio should do with the signal. The honest answer is: not much, on its own. A volume spike is one input, not a verdict. It tilts the risk budget toward being more selective, more hedged, and more attentive to the cost of being wrong on the timing. It is a reason to be cautious about adding aggressively to the most extended names, and a reason to be more careful with leverage. It is not, by itself, a reason to sell.
What Brown is flagging, more precisely, is the kind of regime in which capital preservation begins to matter more than capital accumulation. In late-cycle markets, drawdowns tend to be faster and recoveries slower than they are at the start. That asymmetry changes the calculus on every new position, especially for investors who are sitting on substantial gains and face the question of how much of those gains they are willing to give back before acting.
Stakes and what remains contested
If the late-stage read is correct, the principal losers are the investors who arrive late. That includes retail traders drawn in by year-to-date returns, pension funds that rebalance quarterly and have to buy at the wrong time, and any institution whose performance benchmark forces it to hold the most extended names. The principal winners are those who recognise the shift early and rotate into defensive sectors, higher-quality balance sheets, and shorter-duration exposures — or those who simply sit in cash and wait for the next cycle to set up.
The contested terrain is the duration. Sceptics of the late-stage call argue that AI capex, the energy build-out, and a still-tight labour market can keep the cycle running longer than the historical template suggests. The data on which the call rests is also imperfect. Volume figures are noisy, can be distorted by index rebalances and options expiry, and mean different things at different points in the calendar. The sources do not specify which sectors are driving the recent spike, nor whether it is concentrated in mega-cap names or distributed across the market. Those details would sharpen the read considerably.
The broader structural point is that a bull market does not end with a single piece of news. It ends when a sequence of late-stage tells — narrowing breadth, stretched valuations, rising volume on weakening price action — accumulates until the marginal buyer steps back. Brown's warning is that one of those tells is now flashing. Whether it is the start of the sequence, or the middle of it, or one of the false signals that markets produce throughout every cycle, is the question that the next several months of data will answer.
Desk note: Monexus reports this as a contested cycle read, not a directional call. The wire version of Brown's remark emphasised the late-stage framing; the alternative reading — that rising volume in an uptrend is constructive — appears in the piece in equal structural weight. The judgment is left to the reader.