It is not a regulation. It is a working cap. On a $5 million investable portfolio, a lot of RIAs start alternatives at about 10% — $500,000 — and treat anything past that as a conversation about liquidity, not a badge of sophistication.

The number shows up in different clothes. Bernstein’s allocation work has used 10% as the level where extra expected return still leaves spending and rebalancing intact. KKR’s 2025 RIA survey found nearly half of the firms already putting 10% or more of AUM into private markets. Fidelity’s liquidity grid puts households at $5 million with modest withdrawals in a 10–15% private-markets band. Other shops write 10–25% for the $5–30 million client and keep mass-affluent accounts closer to 0–10%. Ten percent is the floor of the “we actually do this” range, not the endowment model. 

Cerulli’s broader advisor average is still low — a few percent across all books — because most accounts are smaller than $5 million and most firms never built an alts desk. The quiet rule lives at the $5 million desk, not in the average. 

Why $500,000 and not $2 million

A $5 million portfolio that spends 3–4% a year needs cash, tax lots, and the ability to rebalance after a stock drop. Lock 30–40% in 10-year PE funds and a capital call plus a tuition bill arrive in the same quarter. Ten percent leaves $4.5 million in stocks, bonds, and cash that still trade.

Five hundred thousand is also enough to split. One $500,000 check into a single PE fund is a concentrated bet with a J-curve and a gate. The same dollars across private credit, an interval real-estate fund, and a small PE sleeve is a program. Single-manager caps of 5% of the whole portfolio are common for a reason. Colony has talked about 10% real assets, 10% uncorrelated alts, and up to 20% PE/private credit as outer rails — not a default for every $5 million household. Mercer has used 20% private assets and 5% per fund as a starting fence. 

Accreditation is the door, not the allocation. A $5 million portfolio usually clears accredited-investor tests. Qualified-purchaser funds ($5 million in investments) start to appear. That access is why the conversation happens here and barely happens at $400,000.

What “alternatives” means in that 10%

In practice it is not art and wine. For this size it is usually:

•  Private credit or a BDC/interval credit fund for yield that is not a 10-year Treasury.

•  Private real estate or a non-traded REIT/interval fund, sized so one property cycle cannot dominate.

•  A smaller PE or secondaries sleeve if the client can wait.

•  Sometimes a liquid-alt ETF or hedged sleeve for the part that must remain quarterly-liquid.

Endowments run 30%+ because they do not have a mortgage, a daughter’s wedding, or a concentrated stock they might sell next April. Copying Yale with $5 million is how people discover gates. HNW survey data that shows 24–30% in “private and alternatives” often mixes in a family business, a rental property, or crypto. That is not the same as 24% in drawdown PE funds an RIA just subscribed. 

What the 10% is for

Diversification and a different return engine — credit spread, illiquidity premium, real-asset income — not a promise to beat the S&P every year. Fees are higher. Marks are smoother until they are not. Capital calls still arrive. Interval funds that redeem 5% of the fund a quarter are not a checking account.

The rule also protects the adviser. A 40% alts book on a $5 million client who then needs a house down payment is a complaint letter. Ten percent is large enough to matter in a model and small enough to survive a bad vintage.

When firms break it

They go higher when spending is low, the time horizon is decades, and the public book can fund life. They go lower when the client is 72, draws 5%, or already owns a business that is the alternative allocation. They go to zero when the client is not accredited, will not read a K-1, or treats “private” as a synonym for “guaranteed.”

A 10% sleeve on $5 million is $50,000 a year if you think in 10-year commitments and vintage ladders — not one subscription in a hot fund. That pacing is the part that does not fit in a slogan.

The rule is quiet because it is a risk budget, not a product pitch. At $5 million, 10% is usually enough alternatives to change the mix and not enough to strand the household. Past that, you are choosing illiquidity on purpose. That is a different meeting.