The Edge That 24/7 Trading Erased

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Markets are not static. Most people understand this abstractly, the way they understand that languages evolve or that coastlines change shape over centuries, but few investors sit with the concrete reality of what structural market change looks like when you have been watching it happen for 40-plus years.

The picture that emerges from people who have been doing this long enough is not dramatic. It’s incremental. It is, in the words one veteran systematic trader used, glacial, and by the time most people notice it, the terrain has already shifted substantially beneath their feet.

The Opening Range and the Reference Point That Moved

For most of modern financial market history, the open was the most important moment of the trading day. Volume concentrated at the open, price discovery happened there, and the activity that set the tone for everything that followed occurred in the first few minutes after the bell.

Out of this observation came one of the more studied short-term trading concepts in futures market history: the opening range breakout, made famous by Toby Crabel. The logic was simple and durable: If price broke meaningfully above or below the range established in the first minutes of trading, momentum tended to carry it further in the same direction. The open was a trustworthy reference point because it was where real supply and demand were meeting for the first time each day.

This logic worked well for decades. It worked well enough that entire trading programs were built around it, that firms were founded on it, and that serious analysts wrote books about it. And then the terrain started changing.

The first warning came in the 1980s when the US Treasury markets introduced overnight sessions. Traders paying close attention noticed something subtle but important: the follow-through from the prior session's close to the next day's open began to weaken. The opening momentum signal's vitality began to dissipate. At the time, it was a few percentage points here and there, easy to attribute to noise.

But the pattern continued. As global markets extended into continuous 24-hour trading, the open became one moment among many rather than the defining moment of the day. By the time significant volume had already been traded in the Asian and European sessions, the US domestic open no longer served as a true starting point for price discovery. The reference point had not disappeared. It had lost its authority.

Where the Liquidity Went

When the open lost its centrality, the close picked up some of what was left behind. In equity index markets, particularly, volume and price authority have increasingly concentrated at the end of the session. Index rebalancing, passive fund flows, structured product settlement, and the mechanics of end-of-day risk management have all contributed to making the close a more meaningful reference point than it once was.

This represents a genuine structural shift in when and where price discovery happens, and consequently, where the signals that systematic traders rely on actually live. Strategies calibrated to the open have had to recalibrate to survive. Many have not made that adjustment.

The Shift From Breakout to Reversal

Alongside the migration of liquidity, another change has been reshaping short-term price behavior: the decline of trend days and the rise of reversals. The pattern of a market opening and then continuing in one direction for most of the session, what traders call a trend day, has become meaningfully less frequent. What has become more common is the sharp move followed by a sharp counter-move.

Markets make a new overnight low, then rally sharply. A rapid selloff attracts large buyers who absorb the volume and reverse the direction. These reversals are not random events. They reflect the behavior of large participants who need moments of peak volume to execute positions at scale without moving the market against themselves. When scared sellers are all liquidating at once, that is precisely when the largest buyers have the liquidity they need to step in.

This behavioral pattern is older than modern finance. What has changed is the frequency and the scale. There appears to be much more capital deployed against momentum than there was in earlier decades. The growth of options markets, zero-day-to-expiration options activity, multi-strategy funds, and volatility-selling strategies has all contributed to a structural compression of the kind of directional follow-through that once made breakout strategies so reliable.

The math shows up in the data: Where a breakout from a prior high or low might historically have followed through in the expected direction 63 percent of the time, the number might now be closer to 58 percent. That five-point difference sounds modest, but its cumulative effect on strategy performance over years is anything but.

The New Participants and What They Changed

Part of what drove these changes was a wholesale transformation in who is actually making markets. The floor traders of the Chicago exchanges, the locals who provided liquidity in the pits and gave short-term price behavior much of its character, were gradually replaced by algorithmic market makers who operate at speeds measured in microseconds.

These algorithmic participants are not worse market makers than the floor traders they replaced. In many ways they are more efficient. But they behave differently. They are faster to withdraw liquidity when conditions become uncertain. They are more sophisticated in how they manage their own risk across correlated instruments. Their presence has made the order book shallower in ways that show up visually, even as total traded volume has increased substantially. The game being played around prices and volume has become more sophisticated on all sides.

What Has Not Changed

Amid all of this, certain things remain stubbornly valid. The relationship between price and volume, specifically what it means when a large price move occurs on heavy volume versus when it occurs on thin volume, continues to carry genuine information. The concept that volume is effort and price movement is result, that a big effort producing a small result tells you something meaningful about who controls the market at that moment, remains as true as it was when early market analysts first articulated it in the 1920s and 1930s.

What has changed is where the information lives. The signals have not gone away; they have migrated to different time windows, reference points, and market conditions than those that earlier frameworks were designed to capture.

The Lesson for Investors and Allocators

For investors who allocate to systematic strategies or who rely on any kind of rules-based approach to markets, this history carries a straightforward implication: the strategies worth trusting over time are not the ones most precisely optimized to past data. They are the ones built on robust principles that can adapt as the terrain changes.

The strategies that have survived across multiple decades of market structure change share a common feature: they were built on general principles rather than specific parameters. They were designed to capture the underlying logic of how prices and volume interact, not to exploit a particular market behavior at a particular moment. When the moment passed, the strategy could adapt, and when the reference point moved, the framework could accommodate it.

Markets will keep changing, participants will become more sophisticated, and the edges will keep eroding. Understanding this process is not pessimism about markets. It’s what separates investors who can navigate structural change from those who keep following a map that no longer matches the territory.

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This is based on an episode of Top Traders Unplugged, a bi-weekly podcast with the most interesting and experienced investors, economists, traders, and thought leaders in the world. Sign up for our Newsletter or subscribe on your preferred podcast platform so that you don't miss out on future episodes.