Private Markets vs Public Markets: A Return Comparison for Investors

The claim that private markets outperform public markets is one of the most frequently repeated — and most frequently contested — propositions in institutional finance. For high-net-worth and ultra-high-net-worth investors considering an allocation to private equity, venture capital, or other private market vehicles, understanding what the evidence actually shows — and the significant methodological caveats — is essential to making an informed decision.

The Prima Facie Case for Private Market Outperformance

The most commonly cited data source for private equity performance is Cambridge Associates, which aggregates net-of-fee returns from large institutional PE and VC fund databases. Their long-run data consistently shows that top-quartile private equity funds have outperformed listed equity benchmarks — specifically the MSCI World and S&P 500 — over 10, 15, and 20-year horizons.

For example, Cambridge Associates' 2024 Private Investments Benchmark shows:

• US Private Equity: 20-year horizon net IRR of approximately 14%–16% (varying by vintage year)
• Global Listed Equity (MSCI World): 20-year horizon total return of approximately 8%–10% annualised

On these figures, private equity outperforms by 4–6 percentage points annually — which, compounded over 20 years, is a transformative difference. A £1 million allocation growing at 14% for 20 years is worth approximately £13.7 million; at 10%, it is worth £6.7 million.

But these headline comparisons require substantial qualification.

Survivorship Bias and Reporting Problems

Survivorship bias operates at two levels in private market performance data:

Fund-level survivorship: Funds that perform poorly are less likely to have their returns included in commercial databases — managers of failed funds do not typically submit data voluntarily. The effect is that reported database averages are systematically higher than the true average fund return experienced by investors who selected managers indiscriminately.

Vintage year selection: Most long-run private equity return data is dominated by vintage years from the 1990s and early 2000s, when PE funds could acquire companies at lower entry multiples, use higher leverage more cheaply, and benefit from decades of expanding valuation multiples. The structural tailwinds of that era are less available today. Recent vintage years (2015–2023) are showing considerably narrower outperformance vs public markets, and some studies suggest near-parity on a risk-adjusted basis for median funds.

Mark-to-market vs mark-to-model: Listed equities are valued daily at market prices. Private equity portfolios are carried at values determined by the fund manager, typically using discounted cash flow models or comparable company multiples — updated quarterly. During the 2022 market downturn, public equity markets fell 15%–25% while many private equity portfolios reported only modest reductions in NAV, creating an appearance of smoother performance that reflected the valuation methodology rather than genuine resilience.

IRR vs TWR: Why the Metrics Matter

The most fundamental methodological issue in comparing private vs public markets is the difference between Internal Rate of Return (IRR) and Time-Weighted Return (TWR).

IRR is the discount rate that makes the net present value of all cash flows (capital calls, distributions, and residual NAV) equal to zero. It is the standard return metric for private equity because capital is called and returned over time — not invested as a lump sum. IRR is sensitive to the timing of cash flows: a fund that returns capital quickly will show a higher IRR than one that holds investments for longer, even if the absolute gain is identical.

TWR is the standard return metric for public equity portfolios. It eliminates the effect of external cash flows (contributions and withdrawals) and measures the pure investment performance of the portfolio manager, normalised for the timing of cash flows.

Comparing PE IRR to listed equity TWR is an apples-to-oranges comparison. A PE fund with an IRR of 15% may — depending on the actual cash flow profile — correspond to an equivalent TWR of 11%–13% on a dollar-invested basis. Several academic studies (Phalippou, Harris, Kaplan) have attempted to calculate "public market equivalents" (PMEs) that make the comparison on a consistent basis. PME comparisons generally show private equity outperformance, but by a smaller margin than raw IRR comparisons suggest.

The J-Curve

The J-curve is the characteristic performance profile of private equity funds in their early years. Because:

• Fees are charged from inception on committed capital
• Portfolio companies are acquired at initial cost (or written down for early failures)
• Value creation through operational improvement takes time

Most PE funds show negative or near-zero reported returns in years 1–3. Performance improves through years 4–7 as portfolio companies mature, exit activity begins, and distributions are returned to investors. Final net returns are not known until the fund is wound up — which may be 10–12 years after inception for a typical buyout fund, or 15+ years for a venture fund.

This means that for any given vintage year, five to seven years of the fund's life produce "J-curve returns" that look worse than listed equity. Investors in PE who do not understand this, or who rely on short-horizon return comparisons, will systematically underestimate the ultimate return.

For portfolios building a private markets allocation, deploying capital across multiple vintage years (averaging into different parts of different funds' J-curves) helps smooth this effect.

The Liquidity Premium Argument

The economic justification for expecting private market outperformance is the liquidity premium — the additional return investors demand for holding illiquid assets that cannot be sold for 7–12 years. In an efficient capital market, this premium should be positive and persistent, because:

• There is genuine demand for the liquidity of public markets
• Not all investors can bear the illiquidity of private markets (regulatory constraints for some institutions, liquidity needs for others)
• The cost of illiquidity is real and quantifiable

Academic estimates of the fair liquidity premium for PE-style illiquidity range from 1.5% to 3.5% per annum over equivalent-risk public equity. On this basis, a well-constructed diversified private equity portfolio should outperform — but by a meaningfully smaller margin than raw IRR comparisons suggest.

The counter-argument — that in practice, competition for PE assets has compressing the liquidity premium to near-zero or even negative in recent years (PE entry multiples of 13–15x EBITDA in 2021–22, vs 7–9x in the early 2000s) — is legitimate. In periods of cheap debt and abundant capital, the returns to PE buyout strategy have been driven by financial engineering (leverage) and multiple expansion rather than genuine operational value creation, and those tailwinds have reversed.

Access Tiers for Different Investor Types

Private markets access is structured around investor tiers:

Institutional tier (pension funds, endowments, sovereign wealth funds): Direct access to flagship buyout, growth, and venture funds managed by KKR, Blackstone, Apollo, Sequoia, and similar managers. Minimum commitments of $10–$50 million. Performance data shows the strongest long-run returns at this tier, partly because institutional investors access better managers, negotiate better terms, and have the governance to manage complex illiquid portfolios.

UHNW tier (investable assets £10 million+): Access through private wealth feeder funds, family office co-investment, and specialist boutique managers. Minimum commitments of $250,000–$2 million. Product quality and access varies significantly.

HNW tier (investable assets £1 million–£10 million): Access through semi-liquid structures (Long-term asset funds in the UK, ELTIFs in Europe), listed private equity (3i Group, HarbourVest, Pantheon), and co-investment platforms. Listed PE provides liquidity and transparency at the cost of a discount to NAV and public market correlation.

Retail access: Listed PE, PE-exposed investment trusts, and some democratised platforms (Moonfare, Titanbay) now offer lower minimum thresholds. Returns at this tier are typically the least favourable, fees are highest relative to institutional access, and due diligence on manager quality is hardest.

Practical Considerations for HNW Investors

For a HNW individual considering a private markets allocation, key questions include:

• What proportion of investable assets should be illiquid? Most advisers suggest no more than 20%–30% of portfolio value in genuinely illiquid private markets, preserving meaningful liquidity for life events and opportunities
• Can you sustain capital calls over 3–5 years? PE funds call capital as deals are made — typically over the first five years. Investors must have liquid reserves to meet calls when demanded
• How do you access quality managers? The dispersion of returns between top-quartile and bottom-quartile PE managers is enormous — far larger than in listed equity. Manager selection matters far more in private markets than in public markets
• Is listed PE a viable alternative? For those who value liquidity, listed private equity vehicles (3i, Harbourvest Global Private Equity, Pantheon International) provide genuine PE exposure with daily liquidity at typically a 15%–30% discount to NAV

How Global Investments Can Help

At Global Investments, we help clients evaluate private market allocations in the context of their overall wealth strategy, liquidity needs, and risk tolerance. We provide access to institutional-quality analysis of private market managers and vehicles, and help clients understand the genuine risk-adjusted return expectations — not the marketing numbers. If you are considering an allocation to private equity, venture capital, or private credit, contact us for a detailed and balanced assessment.

This article is for informational purposes only and does not constitute regulated financial or investment advice. Private market investments are illiquid, high-risk, and may result in partial or total loss of capital. Past performance is not a reliable guide to future results. Seek professional advice before investing.