The rulebook that governs a fund: UCITS, AIFMD and the '40 Act

Before diversification, an asset must be an "eligible asset." UCITS can only hold specific instrument types: transferable securities (listed equities, bonds), money market instruments, bank deposits, units of other funds, and financial derivatives.

What this rules out for our manager:

• Physical commodities. She cannot buy gold bars or barrels of oil directly. (She can get exposure via eligible derivative instruments in some cases, within limits.)
• Direct real estate. No office buildings.
• Unlisted private companies, beyond a tiny allowance. UCITS caps investment in transferable securities that are not listed or dealt on a regulated market at 10% of net assets (the "trash ratio").

So her beloved pre-IPO startup? Not eligible in size. Her listed mid-cap? Eligible. Now the limits kick in.

The reference text is the UCITS Directive (2009/65/EC). A readable overview sits on the European Commission's investment funds page.

Step 2: Diversification, the 5/10/40 rule

This is the rule that killed her 12% stake. UCITS diversification is built around one memorable formula: 5/10/40.

• A UCITS may invest no more than 5% of net assets in transferable securities from a single issuer.
• This can be raised to 10% per issuer, but the sum of all issuers above the 5% level cannot exceed 40% of the fund.

Worked example. Assume a €500 million fund.

• 5% base limit = €25 million maximum in any one stock.
• Her desired 12% position = €60 million. That breaches the 10% hard ceiling per issuer (€50 million). Illegal. She must cap it at €50 million (10%), and only if she keeps total "above 5%" holdings under 40%.

Let us check that 40% bucket. Suppose she already holds six positions at 8% each. That is 48% sitting in the "above 5%" bucket, already over the 40% limit. So even a fresh 6% position would be blocked, because the aggregate constraint bites before the single-issuer one.

This is why UCITS equity funds are structurally diversified. A manager physically cannot run a 15-stock concentrated book in a plain UCITS wrapper. If she wants that concentration, she needs a different wrapper (an AIF under AIFMD, sold to professional investors).

Group exposure

Issuers in the same group are treated with a combined limit (generally 20% of net assets across the group). So loading up on three subsidiaries of the same parent does not escape the rule.

Step 3: Counterparty and derivative limits

If she uses derivatives (say an index future to equitise cash, or a total return swap), UCITS caps exposure to a single over-the-counter (OTC) counterparty. The limit is typically 10% for credit institutions and 5% otherwise. Total derivative exposure is also constrained: global exposure from derivatives must not exceed 100% of net asset value (calculated via commitment or Value at Risk approaches).

Translation: a UCITS cannot be levered 3x through swaps. Leverage is bounded by design. That is a core investor-protection feature, and a real constraint on strategy.

Step 4: Liquidity, can she sell what she buys?

UCITS must typically offer redemption at least twice a month; most offer daily dealing. That imposes a liquidity discipline on holdings: the portfolio must be sellable fast enough to fund redemptions without fire sales.

Concrete consequence: a thinly traded small-cap that takes 20 trading days to exit at a fair price is dangerous in a daily-dealing UCITS. If redemptions spike, the manager could be forced to sell liquid names first, distorting the portfolio (the "liquidity waterfall" problem seen during the March 2020 stress).

Regulators have pushed liquidity management tools such as swing pricing (adjusting the fund's dealing price so exiting investors bear their own trading costs) and redemption gates. These sit at the heart of due diligence today.

Where AIFMD and the '40 act diverge

Our manager's twin running an AIF (Alternative Investment Fund) under AIFMD faces almost no portfolio composition rules. He can hold that 12% single-stock position, use higher leverage, and buy illiquid private assets. In exchange, AIFMD regulates the *firm*: minimum capital, an independent depositary, remuneration rules, and detailed regulatory reporting (the Annex IV report to the national regulator). The trade-off is clear: freedom on the portfolio, heavier oversight on the manager, and restricted marketing (mostly to professional investors, not retail).

A '40 Act fund in the US sits closer to UCITS in spirit but differs in detail. It has diversification tests (the "diversified" classification requires 75% of assets to meet a 5%-per-issuer and 10%-of-voting-securities test), strict rules on leverage and derivatives (SEC Rule 18f-4), and limits on illiquid holdings (generally 15% of a fund's assets). Different numbers, same philosophy: protect retail investors through hard limits.

Due diligence: what to actually check

When you assess a fund as an allocator or analyst, the rulebook gives you a checklist. Do not take the marketing deck at face value.

1. Confirm the wrapper. Is it UCITS, an EU AIF, or a US '40 Act fund? This tells you the baseline protections instantly. A "concentrated European equity" strategy claiming 20 holdings cannot be a standard UCITS math-wise; ask how.

2. Read the prospectus limits, not just the fact sheet. The prospectus states the actual investment restrictions and any regulator-approved deviations. Check the derivative approach (commitment vs VaR) to gauge real leverage.

3. Stress the liquidity match. Compare dealing frequency to underlying asset liquidity. A daily-dealing fund holding high-yield bonds or small-caps carries redemption risk. Ask whether swing pricing and gates exist.

4. Check the depositary. UCITS and AIFs require an independent depositary that safe-keeps assets and oversees the fund. Its identity and independence matter (a lesson from historical fraud cases where custody was weak).

5. Verify the domicile and regulator. Dublin and Luxembourg dominate European fund domiciles. Each has a specific supervisor. Know who you would call if something breaks.

Why this matters commercially

Regulation is not just compliance overhead; it is product design. The reason UCITS became a global export (widely sold across Asia and Latin America, not only the EU) is precisely that its hard limits create a trusted, standardised product. The rulebook is a selling feature. When a manager chooses a wrapper, she is choosing her investor base, her leverage ceiling, her liquidity promise and her marketing rights all at once.

Key Takeaways

• The wrapper decides the portfolio. UCITS (EU retail), AIFMD (EU alternatives), and the '40 Act (US retail) each impose different hard limits before any investment view applies.
• Memorise 5/10/40. UCITS caps single issuers at 5% (extendable to 10%, with all 5%-plus positions capped at 40% aggregate). This structurally prevents concentrated retail funds.
• Eligibility comes first. UCITS cannot hold physical commodities, direct real estate, or more than 10% in unlisted securities.
• Liquidity must match dealing terms. A daily-dealing fund holding illiquid assets is a redemption risk; check for swing pricing and gates.
• Due diligence means reading the prospectus and confirming the depositary and regulator, not trusting the fact sheet.