Liquidity - The Cost of Converting Assets to Cash

By EC Assets Research Team, Liquidity Strategy · Published 19 May 2026 · Updated 14 October 2026

Liquidity: Liquidity is the ease of converting an asset to cash at a fair price. It encompasses both market liquidity (depth of the market) and funding liquidity (availability of financing). Liquidity premia are a major component of institutional return.

What Liquidity Means

Liquidity is the ability to turn a position into cash quickly at a price close to its fair value. Finance uses the word for two connected things.

Market liquidity belongs to the asset: how much it costs to trade, how large a trade the market can absorb and how quickly prices settle afterwards. Large-cap equities, on-the-run government bonds and major futures contracts are highly liquid; private equity stakes, bespoke derivatives and distressed loans are not.

Funding liquidity belongs to the investor: whether it can finance its positions, meet margin calls and pay redemptions without selling at a bad moment. Brunnermeier and Pedersen (2009) showed how the two feed each other. Falling prices raise margins, higher margins force sales, forced sales push prices down further, and liquidity in both senses disappears at once.

How It Works

Market liquidity has three dimensions, described in Kyle's (1985) model of trading:

A market can be tight but shallow: a narrow quoted spread says nothing about the size behind the quote.

For a portfolio the practical questions are how long an exit takes and what it costs. A common working assumption is that a position can be sold at 20 percent of average daily volume without dominating the market:

$$\text{Days to liquidate} = \frac{\text{Position}}{0.2 \times \text{Average daily volume}}$$

The cost of trading faster is market impact. A widely used rule of thumb, supported by large studies of institutional orders, puts impact at roughly the daily volatility times the square root of the order size as a fraction of daily volume. Because of the square root, a trade four times as large costs only about twice as much per share, which still makes size expensive.

Worked Example

A fund holds three equity positions and assumes it can trade 20 percent of daily volume:

In a sell-off volumes often fall just as everyone wants to sell; the last column, not the third, is the one that matters.

Suppose the fund must sell holding B, whose daily volatility is 2.5 percent. Sold in a single day, the order is 1.25 times daily volume and the rule of thumb puts impact at 2.5% × √1.25 = 2.8 percent. Spread over about six days at 20 percent participation, each day's slice costs 2.5% × √0.2 = 1.1 percent. Patience cuts the cost by more than half, at the price of six days of exposure to further price moves. That trade-off between impact and risk is the core of execution in market microstructure.

When It Applies (and Limitations)

Liquidity is conditional. Markets that are deep in normal times thin out in stress. In March 2020 even US Treasuries, the deepest bond market in the world, saw bid-ask spreads widen sharply and depth collapse as leveraged investors unwound and dealers ran short of balance sheet. Measures estimated in calm periods overstate what will be available when it is needed.

Reported risk understates illiquid risk. Appraisal-based valuations in private equity, real estate and private credit move slowly, which lowers measured volatility and correlation. The exposure is real; it is recognised later. Desmoothing techniques and secondary-market prices give a better picture than reported returns.

Contractual liquidity can be withdrawn. Fund redemption terms, lock-ups and gates mean that an investment's liquidity is partly set by its manager, who can suspend redemptions in exactly the conditions in which an investor would want them.

Rules of thumb are only that. The square-root impact law and the 20 percent participation rate are averages across many trades. Single names, crowded positions and announcement days can behave very differently.

Why It Matters for Institutional Investors

Funding sets the true constraint. An investor using leverage, facing redemptions or carrying unfunded private commitments can be forced to sell regardless of its view. Capital calls tend to arrive faster in downturns, while distributions slow, so the same shock hits both sides of the liquidity budget.

Illiquidity is paid for, but not reliably. Amihud and Mendelson (1986) found that expected returns rise with transaction costs, and Pástor and Stambaugh (2003) found that stocks most exposed to market-wide liquidity shocks earn higher returns. Private-market premiums are harder to measure because smoothed valuations flatter them; an illiquid allocation should be held for its return only if the investor can genuinely wait.

Tiering turns the idea into practice. Classify holdings by time to cash, from same-day to multi-year; match each tier to obligations; size a buffer above stated needs; and test the portfolio against a scenario in which volumes halve, margins rise and capital calls accelerate at the same time. Asset allocation decisions that ignore this step tend to be revisited in a crisis.

References

1. Amihud, Y., & Mendelson, H. (1986). Asset Pricing and the Bid-Ask Spread. Journal of Financial Economics, 17(2), 223-249.
2. Kyle, A. S. (1985). Continuous Auctions and Insider Trading. Econometrica, 53(6), 1315-1335.
3. Amihud, Y. (2002). Illiquidity and Stock Returns: Cross-Section and Time-Series Effects. Journal of Financial Markets, 5(1), 31-56.
4. Pástor, Ľ., & Stambaugh, R. F. (2003). Liquidity Risk and Expected Stock Returns. Journal of Political Economy, 111(3), 642-685.
5. Brunnermeier, M. K., & Pedersen, L. H. (2009). Market Liquidity and Funding Liquidity. Review of Financial Studies, 22(6), 2201-2238.
6. Almgren, R., Thum, C., Hauptmann, E., & Li, H. (2005). Direct Estimation of Equity Market Impact. Risk, 18(7), 58-62.