
Private equity has found its most powerful argument for getting into 401(k) target-date funds:
“Private equity lowers portfolio risk because it has low correlation with public stocks.”
An ERISA fiduciary should be extremely careful before putting that sentence into an investment-committee memo.
Because the apparent diversification can be partly an artifact of how private assets are valued.
Public stocks are marked every trading day. Private-equity holdings may be valued periodically using estimates, models and manager judgments. Market movements therefore don’t necessarily appear immediately in reported NAV.
The result can be:
Smoothed NAV → artificially low measured volatility → artificially low measured correlation → artificially attractive Sharpe ratio → apparent diversification benefit.
The economic risk hasn’t necessarily disappeared.
The ruler changed.
And there is unusually strong independent support for that proposition.
Even T. Rowe Price warns that smoothing distorts diversification statistics
This isn’t merely an argument made by private-equity critics.
T. Rowe Price’s analysis of private-asset diversification acknowledges that appraisal-based valuations and the absence of mark-to-market pricing can make private-asset performance incomparable with public assets.
Its conclusion is particularly important: smoothed results do not accurately represent the actual volatility and correlation characteristics of private investments. Its analysis found that, over longer periods that diminish the smoothing effect, private-equity volatility was comparable with large-cap public equities over one-year periods and higher over rolling three-year periods.
That is potentially devastating to the simplistic TDF sales pitch.
Suppose an optimizer is given:
| Input | Public equities | Reported PE |
| Standard deviation | 18% | 10% |
| Correlation | 1.00 | .50 |
| Expected return | 8% | 10% |
Of course the optimizer wants PE.
But suppose economic reality after correcting for stale pricing looks more like:
| Input | Public equities | Unsmoothed PE |
| Standard deviation | 18% | 20% |
| Correlation | 1.00 | .85 |
| Expected return | 8% | 10% |
The alleged diversification miracle largely disappears.
Garbage risk statistics in → fiduciary-looking efficient frontier out.
The academic evidence is even stronger
Boyer, Nadauld, Vorkink and Weisbach published an important Journal of Finance paper using PE secondary-market transactions.
Their conclusion:
“Net asset values are too smooth.”
They found that NAVs fail to reflect changes in discount rates and warned that ignoring that variation can result in misallocation of capital.
That goes directly to the 401(k) issue.
The relevant fiduciary question isn’t:
“What standard deviation did the PE manager report?”
It is:
“What would the volatility, beta and correlation look like if these assets were continuously market-priced like everything else in the target-date fund?”
A fiduciary who doesn’t ask that question could be comparing apples with periodically appraised oranges.
Recent NBER research provides another warning. Ercan, Kaplan and Strebulaev found that the history of private-equity interim valuations contains information beyond the latest reported valuation; greater valuation staleness and repeated markdowns help predict subsequent outcomes.
In other words, the latest NAV isn’t necessarily the whole risk story.
Bailey and López de Prado: serial correlation can hide enormous downside risk
David Bailey and Marcos López de Prado provide another piece of this puzzle. https://lnkd.in/eqvbp7qC
Their research examined the consequences of treating serially correlated investment returns as though returns were independent.
Their finding was remarkable:
Ignoring serial correlation can underestimate downside potential by as much as 70%.
Their paper concerns hedge-fund strategies rather than specifically PE target-date funds, so I would not claim they proved that PE risk is understated by 70%.
But the methodological warning is directly relevant.
When smoothed or stale marks create serial correlation, conventional risk measures can badly mischaracterize the underlying risk.
An ERISA fiduciary therefore shouldn’t accept a consultant’s standard deviation, Sharpe ratio or correlation matrix without asking:
How were the private-market returns adjusted for smoothing and serial correlation?
If the answer is they weren’t, the supposedly sophisticated asset-allocation model may be built on a fundamental statistical mismatch.
This is the same “Risk Illusion” we identified with TIAA
The structure closely resembles the problem I previously identified with TIAA’s target-date modeling.
TIAA’s annuity doesn’t fluctuate like a bond fund because there isn’t a continuously traded security producing a market price every day. The crediting process and insurance structure smooth what participants see.
That can make an illiquid contractual asset look statistically safer than a liquid security.
The CommonSense analysis called this “fake volatility”: risk can be transferred or hidden without disappearing.
Private equity potentially brings the same problem to the equity side of the glidepath.
Put the two together and a next-generation TDF could theoretically contain:
Public Stocks + Bonds + Private Equity + Private Credit + Real Estate + Annuities
and report beautifully diversified historical statistics.
But some of the apparent diversification may arise precisely because the assets aren’t being priced on the same basis.
That is not necessarily diversification.
It can be accounting diversification.
Why this creates ERISA litigation exposure
This is where the issue gets much more serious.
ERISA doesn’t ask whether a consultant’s PowerPoint produced an attractive efficient frontier.
The fiduciary must undertake a prudent process.
The Department of Labor’s PE guidance specifically recognized that private equity presents greater complexity, longer time horizons, less liquidity, different regulatory/disclosure standards, more complicated valuation and typically higher fees. It said fiduciaries considering PE should conduct an objective, thorough and analytical process, secure sufficient information to understand the investment and its risks, and compare a PE-containing fund against alternatives without PE.
Important current-law qualification: the Biden-era 2021 Supplemental Statement was rescinded in August 2025, so it should not be presented as current DOL policy. But its description of the underlying valuation/liquidity problems—and the underlying fiduciary principles—remains historically useful evidence of risks regulators specifically identified.
The original 2020 Information Letter itself did not authorize standalone participant PE investments; it addressed PE as a component of professionally managed asset-allocation funds.
That makes the target-date fund exactly where this fight is likely to occur.
The plaintiff’s discovery request practically writes itself
Imagine the investment committee approves a TDF containing 10% PE because the consultant says PE reduces volatility and improves diversification.
Five years later participants sue.
Plaintiffs ask for:
- Every correlation matrix presented to the committee.
- The raw return series underlying those correlations.
- Reported and unsmoothed PE volatility.
- The methodology used to correct quarterly/stale valuations.
- Serial-correlation adjustments.
- Public-market-equivalent analysis.
- Secondary-market valuations.
- Stress-period correlations.
- The underlying LPAs and side letters.
- Every analysis comparing the PE TDF with a low-cost liquid TDF without PE.
Then comes the deposition:
Q. You concluded private equity reduced the target-date fund’s risk?
A. Yes.
Q. You knew public equities were priced daily?
A. Yes.
Q. You knew the private investments weren’t?
A. Yes.
Q. What adjustment did you make before comparing their standard deviations and correlations?
A. None.
That’s the problem.
The WSJ article raises the fiduciary standard even further
Jason Zweig’s new Wall Street Journal article warns ordinary investors about precisely the characteristics that can disappear behind the PE-diversification sales pitch: infrequent and potentially dubious valuations, limited liquidity, high and variable fees, adviser incentives and the complexity of private funds.
Zweig recommends asking detailed questions and getting the answers in writing.
Jason Zweig — What to Ask When Your Adviser Pushes Private Funds
That creates an uncomfortable ERISA question:
If the Wall Street Journal says a retail investor should question the valuation and liquidity of a $50,000 private investment, what excuse does an ERISA fiduciary have for accepting a consultant’s correlation matrix before putting $500 million of workers’ retirement money into PE?
And then we reach the CIT
This is where your recent contract work and the risk-smoothing argument come together.
A conventional mutual fund provides investors a registered security with substantial standardized public disclosure.
The emerging private-market TDF can instead look like:
401(k)
↓
Target-Date CIT
↓
Private-Market CIT / Feeder
↓
Conduit / Alternative Investment Vehicle
↓
Private-Equity Partnership
↓
Portfolio Companies
Your recent CommonSense article argues that these structures can provide much less participant visibility into the underlying contracts and economics.
CommonSense — SEC Mutual Fund Standards Are Slipping, But Not Fast Enough for Private Equity
I would make one legal distinction very clear: a state-regulated CIT does not itself legalize bad valuation, an imprudent investment process, or an ERISA prohibited transaction.
Its importance to your thesis is different:
The CIT can obscure the evidence necessary to test the sales pitch.
The participant sees:
“2055 Target Retirement Fund.”
The fiduciary may be shown:
“Lower volatility + lower correlation + higher expected return.”
But underneath those statistics can sit bespoke PE contracts, GP valuations, feeder vehicles, different liquidity rights, leverage, affiliated fees and other contractual economics that aren’t apparent from the TDF’s name or headline statistics.
That makes your contract article the second half of this story.
CommonSense — The Contracts Private Equity Doesn’t Want 401(k) Participants to See
Anderson v. Intel makes this especially dangerous
Anderson v. Intel Corporation Investment Policy Committee is about whether an ERISA underperformance complaint must allege a “meaningful benchmark” to survive dismissal. The underlying Intel plans invested through target-date/global-diversified funds containing alternative investments, including PE and hedge funds.
Now combine that litigation issue with private-market smoothing.
The PE industry can potentially argue on the front end:
“Our low correlation proves PE reduces risk.”
And defendants can argue after litigation begins:
“Plaintiff hasn’t identified an appropriate meaningful benchmark.”
But how does the participant construct the correct benchmark if the underlying contracts, valuations, leverage and actual economic exposures aren’t publicly available?
That is why valuation opacity + contractual secrecy + meaningful-benchmark pleading requirements could become an extraordinarily powerful defense mechanism.
Your argument shouldn’t be that every low correlation is “fake.”
It should be harder to rebut:
A fiduciary cannot prudently rely on reported PE correlation and volatility without determining whether stale or discretionary valuations materially suppress those statistics.
The fiduciary litigation test
I would end the piece with this.
Before a fiduciary accepts the statement “private equity reduces TDF risk,” demand six numbers:
Reported PE volatility.
Unsmoothed PE volatility.
Reported stock/PE correlation.
Unsmoothed stock/PE correlation.
Stress-period correlation.
Secondary-market discount to reported NAV.
Then demand the methodology and underlying data in writing.
If the PE manager won’t provide them, don’t let the consultant put “diversification benefit” in the investment committee minutes.
Because after the lawsuit is filed, that phrase may become Exhibit A.
Bottom line
Private equity does not become safer because its price moves less often.
An asset that isn’t marked doesn’t have zero volatility. It has unreported volatility.
And a target-date fund doesn’t become diversified merely because a spreadsheet combines daily-priced public securities with quarterly manager-valued private assets and produces a low correlation coefficient.
For an ERISA fiduciary, mistaking valuation smoothing for risk reduction isn’t sophisticated diversification. It is potentially discoverable evidence of a flawed fiduciary process.









