What Liquidity Costs and What It PaysSome background helps

Liquidity is a service somebody sells and somebody buys. Which side you are on determines whether it is a cost or a return — and most people are on the buying side without knowing it.

Liquidity is a trade, not a property

• You are buying liquidity whenever you need to transact now: paying the offer, hitting the bid, exiting a fund on a redemption date. The cost is immediate and measurable.
• You are selling liquidity whenever you can wait: posting a limit order, holding an off-the-run bond to maturity, locking capital into a vehicle with notice periods. The payment arrives as extra yield or a better entry price.
• Most people buy liquidity they do not need — trading at market when they had no deadline — and simultaneously fail to get paid for the illiquidity they are in fact carrying.

The three components of a liquidity cost

• Spread dominates for small orders, impact for large ones, delay for anything worked over hours or days.
• They trade off against each other. Trading faster reduces delay risk and increases impact; trading slower does the reverse. There is no execution that avoids all three.
• The number to compare against is your expected edge. If the round trip costs 60 basis points and the position is expected to earn 200 over a year, a third of the first year is spent on entry and exit.

The illiquidity premium: real, and frequently overstated

• It is genuine compensation. An off-the-run government bond yields more than the on-the-run one for no credit reason at all — the difference is purely that fewer people will take it off your hands.
• It is earned only if your horizon actually matches. The premium is payment for not needing to sell. Someone who might need to sell has taken the risk without the ability to collect the payment.
• Reported volatility of illiquid assets is understated, because infrequent or model-based valuation smooths the series. A quarterly-valued private holding and a daily-priced public one can have identical economics and very different-looking risk statistics.
• Smoothing also understates correlation, which makes illiquid assets look like better diversifiers than they are. This is a measurement artefact, not a portfolio benefit — see diversification.
• The honest version: the premium is real, the risk statistics flattering it are not, and the two effects are frequently confused for one another.

Liquidity disappears when it is needed

• Market makers widen or withdraw under stress, because their inventory risk rises exactly when everyone wants the same side. This is rational behaviour, not a failure.
• Correlated selling makes it worse. When many holders face the same margin call or the same redemption wave, the exit is one door — the mechanism in 1998, 2022 and every liquidity event between.
• Liquidity is a property of a market at a moment, not of an instrument. The same bond is liquid on a quiet Tuesday and not on the morning that matters.
• The planning implication: size positions on stressed liquidity rather than normal liquidity, because the day you need to exit is by definition not a normal day. This is the liquidity check in the sizing playbook.

Where the wrapper changes the liquidity, and where it only appears to

• An ETF over illiquid bonds is liquid on the exchange and not underneath. In calm markets the arbitrage mechanism keeps the two in line; under stress the ETF price can lead the stale underlying valuations, which looks like a discount and is often the more honest price.
• An open-ended fund over illiquid assets promises daily dealing it cannot always deliver. Gating is the promise being renegotiated, and it happens at the worst moment by construction — one of the six patterns in how products fail.
• A closed-ended vehicle does not promise it at all, and prices the mismatch openly as a discount to net asset value. That discount is uncomfortable and honest — the discount calculator shows what closing it would be worth, and why waiting for that is a hope rather than a return.
• A structured note's liquidity is the issuer's willingness to quote. There is no market; there is a counterparty.

Four practical questions

• How many days of average volume is my position? Above one or two, the exit is a project rather than a trade.
• What did the spread look like in the last stress episode, not today?
• Am I being paid for the illiquidity I hold — is there a visible yield or price concession, or am I carrying it for free?
• Does my horizon genuinely match the asset, including the scenario where I need money for a reason unrelated to markets?