Free lesson · Fund operations & capstone

Match portfolio liquidity to funding promises

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Start with the idea

A solvent fund can still run out of cash before it can sell assets. Liquidity analysis links position size, market capacity, margin demands and investor withdrawals on the same calendar.

Symbols, units & horizon

Qᵢ: signed holding quantity
|Qᵢ|: liquidation quantity magnitude
pᵢ: assumed fraction of daily volume that can be traded
ADVᵢ: average daily volume in matching instrument units
Days: trading days under a constant-volume approximation
Available cash: immediately usable currency
Stressed margin: scenario margin requirement
Scheduled outflows: currency obligations
Cash buffer: currency remaining after those uses

When and why to use this

Use days-to-liquidate and stressed cash buffers before sizing less liquid strategies. Recompute under joint volume and margin shocks.

{d a y s t o l i q u i d a t e}_{i} \approx \frac{| Q_{i} |}{p_{i} A D V_{i}}

Algebra and arithmetic

Divide the position by daily execution capacity

Daily capacity at participation fraction p is p×ADV in units/day. Dividing position units by this capacity gives days.
Rearrange to $Q_{m a x} = D_{m a x} p A D V$ for a liquidation-horizon constraint. Round up when planning complete whole trading days.

Work it by hand

Q=1m shares, ADV=500,000,p=.1 → 20 days. If volume halves, the estimate becomes 40 days before impact.

Q is the number of units held, ADV is average daily volume in the same units, and p is the allowed participation fraction. This estimate assumes stable volume, ignores price impact, and can be very optimistic in a stress. Short books additionally depend on borrow and margin conditions.

c a s h b u f f e r = a v a i l a b l e c a s h - s t r e s s e d m a r g i n - s c h e d u l e d o u t f l o w s

Algebra and arithmetic

Balance stressed cash uses against available cash

Begin with cash that can actually be accessed by the deadline. Subtract required stressed margin and scheduled outflows.
If buffer B is negative, required additional funding or asset-sale cash is −B. Do not count collateral twice as both free cash and already posted margin.

Work it by hand

Cash $3m, stressed margin $2m, outflows $1.5m gives buffer −$.5m: a $500,000 funding need.

A positive accounting NAV does not ensure enough cash to meet a margin call today. Redemption terms, financing tenor, collateral eligibility, counterparty concentration, and market liquidity must be assessed together. Model several stresses jointly rather than assuming that normal daily trading capacity persists.

Map positions into liquidation buckets using both ordinary and stressed assumptions.
Separate committed cash obligations from contingent margin and borrow demands.
Specify valuation escalation for stale or disputed prices and independent oversight for hard-to-value positions.

Python implementation

Self-contained teaching example. Python 3.10+; dependencies and input conventions are shown in the code and notation. Run in your own Python environment.

def liquidation_days(quantity, daily_volume, participation):
    if daily_volume <= 0 or not 0 < participation <= 1:
        raise ValueError("Positive volume and participation in (0,1] required")
    return abs(quantity)/(participation*daily_volume)

def stressed_cash_buffer(available_cash, stressed_margin, scheduled_outflows):
    return available_cash-stressed_margin-scheduled_outflows

print(liquidation_days(500000,1000000,.1), stressed_cash_buffer(1e6,6e5,3e5))

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