What role might private investments play in a portfolio?

Why concentration risk matters in private markets

Concentration risk is the chance that a small number of positions, or a single one, drives the bulk of your portfolio's outcome. It exists in public markets too. Private markets sharpen it for two reasons: outcomes are more extreme, and you cannot easily exit a position that has grown too large.

Private investments have uneven outcomes

Returns in private markets are not evenly distributed. A small number of investments often drive most of the gains, while many others return little or nothing. This pattern — sometimes called a power law — shows up across venture and growth investing. The implication runs against intuition. If most of your return is likely to come from a few winners you cannot identify in advance, holding too few positions raises the odds you simply miss them.

Illiquidity amplifies concentration risk

In public markets, a position that grows too large can be trimmed in an afternoon. Private markets do not offer that. Exits may take years to materialize, arriving through an acquisition, an IPO, or a secondary sale that may or may not be available when you want it.

That changes what concentration means. A public investor who is overexposed has a problem they can fix today. A private investor who is overexposed has a problem they may carry for years, with the size of the investment fixed in place while its value moves. Time, here, is part of the risk.

How investors think about position sizing

Position sizing in private markets comes down to a single tension: conviction pulls toward fewer, larger investments, and diversification pulls toward more, smaller ones. There is no formula that resolves it. There are only tradeoffs you can make deliberately or by accident.

Balancing conviction and diversification

A high-conviction position can be the right call. It can also be the one that sinks a portfolio. Concentration cuts both ways: it raises your upside if you are right and deepens the hole if you are wrong. The investor who puts a quarter of their capital into one company has not made a smarter investment than the one who spread it across ten — only a more concentrated one.

The useful question is not "which do I believe in most" but "how much of my outcome am I comfortable handing to a single decision." Conviction tells you what to buy. Sizing tells you how much your portfolio can survive being wrong about it.

Exposure by issuer, sector, and stage

Counting your positions is the easy part. The harder part is seeing how correlated they are. Two investments in different companies are not diversified if both are late-stage AI infrastructure plays exposed to the same customers, the same capital cycle, and the same wave of sentiment.

Real diversification means looking at exposure along several axes at once: the issuer, the sector, and the stage of company. Too much overlap on any of them increases portfolio correlation, which means your positions tend to move together — and a portfolio that moves together is more concentrated than its position count suggests.

How portfolio size changes by investment strategy

The right number of private investments depends heavily on what you are investing in. Failure rates, structure, and liquidity all shift the math, so a sensible number for one strategy can be reckless or needlessly cautious for another.

Direct startup investing

Direct startup investing usually calls for the broadest diversification, because early-stage failure rates are high. Many young companies do not return capital, and the ones that carry a portfolio are rarely obvious at the outset. That combination pushes direct investors toward more positions rather than fewer.

This is one reason direct startup portfolios tend to include more positions than other private strategies. A small number of concentrated early-stage bets carries less diversification than the term 'portfolio' implies — the outcome depends heavily on which few positions are held. 

SPVs and pooled vehicles

Special purpose vehicles and other pooled structures change the unit of diversification. An SPV lets a group of investors pool capital into a single company or, in some structures, across several. That can give an individual exposure to a deal they could not access alone, or to a basket of companies inside one vehicle.

Pooled vehicles do not erase concentration risk — an SPV into one company is still a single-company investment. But they can be a building block for diversification, letting you assemble exposure across more deals than you could reach writing checks one at a time.

Funds and secondaries

Funds and secondaries each carry their own concentration profile. A fund spreads capital across a manager's portfolio, which diversifies company risk but concentrates manager and vintage risk. Secondaries — buying existing stakes in private companies rather than primary shares — can add positions at later stages, often with more visibility into the company than an early-stage investment allows.

Different structures create different concentration profiles, and that is the point. The strategies are not interchangeable. Mixing them is one of the more reliable ways to avoid being concentrated without realizing it.

Common concentration mistakes investors make

Most concentration problems are not chosen on purpose. They accumulate. A position grows, a theme gets crowded, or liquidity needs collide, and a portfolio that looked diversified on paper turns out to rest on one or two load-bearing assumptions.

Overexposure to one company

The most direct mistake is letting a single investment dominate the portfolio. It can happen at entry, through an oversized initial check, or over time, as a winner appreciates until it quietly becomes most of your exposure. Either way, the result is the same: one company's fortunes now stand in for your portfolio's.

Chasing thematic concentration

Sector concentration is subtler and just as common. Loading heavily into one theme — whatever is in favor that year — feels like conviction. It often is. It also ties your outcome to a single cycle. When the theme cools, everything in that bucket tends to cool together, and the diversification you thought you had across companies turns out to have been a single investment on a sector.

Ignoring liquidity overlap

The least visible mistake is liquidity overlap. Hold enough illiquid positions and you can find yourself cash-constrained even while your portfolio looks healthy on paper, because none of it can be converted when you need it. Several long-dated positions maturing on no particular schedule can leave you asset-rich and cash-poor at the same moment — a risk that never shows up in a list of holdings.

How sophisticated investors manage concentration risk

Experienced private investors treat concentration as something to manage continuously, not solve once. Two habits do most of the work: diversifying across timelines and rebalancing exposure as the portfolio drifts.

Diversifying across timelines

One way to manage concentration is to diversify across time, not just across companies. Combining venture, growth, and secondaries spreads exposure across stages that mature on different horizons. Early-stage investments may take many years to resolve; later-stage secondaries can sit closer to a potential exit. A portfolio that blends them is less likely to have all its outcomes — and all its liquidity — arrive, or fail to arrive, at once.

Rebalancing exposure over time

Private portfolios drift. As valuations change, a position that was sized responsibly at entry can grow into an outsized share of the whole without you doing anything. Managing that drift is harder than in public markets, where you can simply trim. In private markets, rebalancing often means directing new capital toward underweight areas rather than selling overweight ones, since selling may not be an option. The work is ongoing, and the investors who do it well tend to revisit their exposure on a schedule rather than waiting for a position to force the issue.

How Augment helps investors evaluate portfolio concentration

Augment is a private marketplace built to give investors access to a wider range of private market opportunities — the raw material for a more diversified private portfolio. Breadth of access is what makes diversification possible in the first place; you cannot spread exposure across opportunities you cannot reach.

The platform supports exposure across different stages and liquidity profiles, from earlier-stage names to later-stage secondaries, so investors can think about their holdings in terms of timeline and not only sector. Through Augment's pre-IPO investment platform, investors can weigh individual opportunities within the context of a broader portfolio rather than in isolation, which is where concentration and liquidity tradeoffs actually get decided. For a view pre-IPO companies list offers a starting point for that comparison.

None of this removes the risks described above. Private investments remain illiquid, long-dated, and uncertain. What better access and clearer comparison can do is make the tradeoffs visible, so the shape of your portfolio is something you choose rather than something you discover.

Final takeaways on concentration risk in private markets

Private portfolios ask you to hold two ideas at once: conviction in specific opportunities, and enough diversification that no single one decides your outcome. The number of investments you hold is how you reconcile them.

Concentration risk in private markets is sharper than in public ones because it is amplified by illiquidity and long timelines — the size of a bet is fixed in place while its value moves, sometimes for years. Sound position sizing accounts for that by looking past the headcount of holdings to the real exposure underneath: by issuer, by sector, by stage, and by when each position is likely to resolve.

Augment gives investors broader access to private market opportunities and the context to compare them, so that the balance between conviction and diversification is a deliberate choice. The number of private investments held ultimately reflects how much of an outcome an investor is willing to concentrate in any single position.