A Haircut Decides How Much You Can Borrow Against Something
Lending against collateral means lending less than it is worth. The size of that gap moves with conditions, and when it moves everyone is forced to sell at once.
The Concept
A borrower pledging collateral worth 100 does not receive 100. They receive less, and the difference is the haircut.
A 5 percent haircut means borrowing 95 against 100 of collateral. The gap protects the lender: if the borrower defaults and the collateral has fallen in value before it can be sold, the lender is still covered.
The haircut is the lender estimate of how far the collateral could fall in the time it would take to seize and sell it. It is a volatility and liquidity assumption expressed as a number.
What Determines the Size
| Factor | Effect on haircut |
|---|---|
| Price volatility | Higher volatility, larger haircut |
| Liquidity | Liquid assets, smaller haircut |
| Time to liquidate | Longer, larger |
| Correlation with borrower credit | Wrong way risk, much larger |
| Overall market conditions | Stress widens everything |
Wrong way risk deserves attention. Collateral that falls in value precisely when the borrower is likely to default provides far less protection than its price suggests. A bank pledging its own securities, or a borrower pledging assets from its own sector, creates exactly this.
The Leverage Relationship
Haircuts determine maximum leverage directly. A 2 percent haircut permits borrowing 98 against 100, which supports a position 50 times equity. A 10 percent haircut permits 10 times.
The relationship is not linear. Small changes in the haircut at low levels produce very large changes in permitted leverage, which is why the tightening of haircuts in a stress event is so consequential.
The Procyclical Mechanism
This is where haircuts become a systemic issue rather than a bilateral credit term.
In calm conditions, volatility is low, so haircuts are low, so leverage is high. Positions are built on that basis across many institutions.
When volatility rises, lenders widen haircuts. Borrowers must post additional collateral or reduce positions. Many reduce positions, which means selling, which pushes prices down and raises volatility further, which widens haircuts again.
The loop runs without anyone behaving irrationally. Each lender is prudently protecting itself, and the aggregate effect is a forced deleveraging across the system.
Where It Has Mattered
The 2008 crisis included a severe version of this in repurchase agreement markets. Haircuts on mortgage related collateral widened dramatically and in some cases the collateral became unfinanceable at any haircut, which removed the funding underpinning large parts of the system.
March 2020 produced a compressed version, with margin and haircut increases forcing simultaneous selling across asset classes, including in normally safe assets that were sold because they could be.
The 2022 United Kingdom pension episode was the same mechanism in a different market: collateral calls on hedging positions forced sales of the assets that were being hedged.
The Regulatory Response
Because haircuts are procyclical, there have been proposals for minimum floors that would not fall in good times, limiting how much leverage can be built during calm periods.
Implementation has been partial. Minimum haircut standards exist for some transaction types, and setting a floor high enough to matter means constraining activity during precisely the periods when nobody perceives risk, which is politically and commercially difficult.
The Bottom Line
A haircut is the gap between collateral value and the amount lent against it, sized to the lender estimate of how far the asset could fall before it could be sold. It sets maximum leverage directly, and because it widens in stress it converts a price decline into forced selling across every leveraged holder simultaneously. Nobody has to act irrationally for the loop to run.