So many portfolios are built for the economy that just happened. For most of the 2010s, that meant an economy short on demand, and many of the rules of portfolio construction that emerged during that decade followed from that single fact.
A decade later, the fact has changed. And many of the rules built on top of it need to change too.
The Decade That Made Diversification Easy
Picture the 2010s as a world defined by a shortage of demand. Growth was scarce, so central banks did what central banks do when growth is scarce: they pinned interest rates near zero and pushed investors toward riskier assets in search of return.
That policy response had a chain of effects. It suppressed volatility across markets, and it made weak growth rather than inflation the primary concern for investors and policymakers alike. Because almost everyone shared that same worry, stocks and bonds tended to move in opposite directions. Anything that damaged growth expectations also gave central banks reason to lower rates, pushing bond prices higher just as equities were coming under pressure.
That made diversification feel almost effortless. Own stocks for growth, own bonds for protection, and let the correlation between them do much of the work. But that negative correlation was never a permanent law of markets. It was the product of a particular economic regime. And regimes change.
When the Economy Ran Out of Slack
The change started during the pandemic and never really stopped. Supply chains investors had assumed were resilient turned out to be fragile the moment a global shock tested them. The war in Ukraine delivered a second lesson, this time about energy. And now the AI buildout is delivering a third, showing up in bottlenecks around leading-edge chips, power generation, and the sheer amount of capital required to keep the buildout going.
This is a shift from a demand-constrained world toward a supply-constrained one. A shortage of demand can often be addressed with policy. Central banks can cut rates, governments can spend more money, and policymakers can make risk-taking more attractive. A shortage of supply is different. Interest-rate cuts do not manufacture advanced chips. They do not build power plants, expand electricity grids, or suddenly create more energy capacity. Those physical constraints take time to resolve.
That changes the inflation picture. It changes the role of interest rates. And ultimately, it changes what investors should expect the different parts of a portfolio to do.
What is the Role of Bonds Now?
In a demand-driven world, bonds performed two jobs at once. They generated returns through duration, as falling interest rates lifted the value of long-dated bonds. And they diversified equity risk because weaker growth usually meant lower rates, allowing bond prices to rise when stocks were struggling.
In a more supply-constrained world, where inflation and scarcity matter alongside growth, that second function becomes much less dependable. The answer is not to abandon bonds. It is to give them a different job description.
Rather than relying as heavily on duration and the assumption that bonds will rally whenever equities fall, the more durable case for fixed income increasingly rests on income itself: a diversified mix of government bonds and public and private credit, spread across corporate debt, emerging market credit and other sources of cash flow.
Income is a different kind of ballast. It can still suffer when credit conditions deteriorate, but it does not require stocks and bonds to maintain the same negative correlation that made the traditional portfolio work so well during the previous regime.
That leaves a bigger question. If bonds are no longer providing the diversification they once did, where should investors look for it instead?
Where to Find Diversification Today
One answer is market-neutral hedge fund strategies, designed to generate returns without depending heavily on whether markets themselves rise or fall. Another, which should surprise no regular reader of this blog, is Trend Following. The interesting thing is that they approach the same diversification problem from almost opposite directions.
Market-neutral strategies try to remove broad market direction, offsetting long and short exposures in an attempt to isolate something closer to pure alpha. Trend Following embraces market direction, but without needing to know in advance what that direction will be. It can go long or short across equities, bonds, currencies and commodities as sustained trends emerge. That distinction becomes particularly valuable when the source of portfolio stress is no longer predictable.
The next major shock might come through equities. But it might just as easily emerge through inflation, interest rates, currencies, commodities, or some combination of them. Trend Following does not require investors to know where the shock will appear, and crucially, it does not require stocks and bonds to behave according to a familiar correlation pattern. It requires something different: markets that move far enough and persistently enough for those moves to become opportunities.
Market-neutral strategies bring a different set of lessons. The 2007 quant crisis was a reminder that calling something market-neutral does not make it risk-neutral. Strategies that appeared independent could still share hidden factor exposures, crowded positions and common sources of leverage. When those positions were unwound together, correlations appeared precisely when investors least wanted them.
The lesson was not to abandon systematic investing. It was to become much more deliberate about what risks were actually being neutralized and to isolate return streams that were genuinely different rather than merely labelled differently.
Neither market-neutral investing nor Trend Following is a permanent hedge. Market-neutral strategies can struggle when supposedly independent positions suddenly become correlated. Trend Following can struggle when markets repeatedly reverse direction or fail to establish meaningful trends. But that is also the point.
True diversification does not come from finding one strategy that protects against everything. It comes from combining return streams that succeed and fail for different reasons. A strong multi-strategy allocation therefore becomes less about finding the perfect hedge and more about making sure the portfolio is never built around a single point of failure.
The AI Valuation Question
No conversation about the current market gets far without addressing AI valuations, and the usual bubble debate misses a detail worth thinking about.
Many of the companies sitting at the center of the AI buildout, particularly suppliers of memory chips and other critical inputs, are generating extraordinary profits. Yet several trade at less than ten times forward earnings, a number BlackRock's Mike Pyle has highlighted as evidence that the market is not treating this the way it treated technology stocks in the late 1990s.
A classic bubble tends to combine extraordinary expectations with extraordinary valuations. Here, at least in parts of the AI supply chain, extraordinary profits are being awarded surprisingly ordinary multiples. The market may be telling us something.
Those profits are coming from bottlenecks rather than necessarily from permanent competitive advantages, and bottlenecks do not last forever. Economics has a simple way of describing this. In the short run, factors of production are fixed. That scarcity is precisely what creates bottlenecks and the outsized profits that come with them. In the long run, factors of production become more flexible. New suppliers enter, existing companies expand capacity and the scarcity that created those profits begins to fade.
Seen that way, a low multiple can simply be the market's way of saying today's earnings are unusually high, not permanently so. That is very different from the late 1990s, when investors often paid enormous multiples for profits that had not yet arrived.
Building Around a Different Center of Gravity
None of this means abandoning growth exposure. Growth still belongs at the core of a well-constructed portfolio. What changes is everything built around it.
Bonds move from being primarily a duration hedge toward being more of an income engine. Diversification moves from something bonds once provided almost automatically to something investors have to seek out deliberately, through strategies such as market-neutral investing and Trend Following that depend on fundamentally different sources of return.
Instead of starting with fixed allocations to stocks, bonds and alternatives, the more useful question becomes what jobs the portfolio actually needs performed. It needs growth, it needs income, and it needs diversification that does not depend on the growth and income pieces behaving exactly as they did during the last economic regime.
That is essentially the logic behind what some large asset managers call a total portfolio approach. Rather than organizing the portfolio around asset-class labels, it organizes it around the underlying drivers of risk and return.
Seen through that lens, equities might provide exposure to growth and themes such as AI and scarcity. Fixed income can provide contractual income. Market-neutral strategies can seek returns independent of broad market direction. Trend Following can provide exposure to sustained price movements wherever they emerge.
DISCLAIMER: This article is based on a conversation from Top Traders Unplugged and reflects themes, ideas, and perspectives discussed during the episode. The views expressed are those of the guest and participants in the conversation and should not be interpreted as investment advice or as the official views of Top Traders Unplugged.
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