What prime brokerage is (plain English)
Prime brokerage is a bundle of services that helps funds operate efficiently:
- financing (margin / leverage)
- securities lending
- trade clearing and settlement
- custody and reporting
- operational support
The business model (why the bank does it)
- Earn financing spreads and fees
- Monetize balance sheet and collateral
- Deepen client relationship across trading and capital services
Where the risk hides
1) Counterparty default + wrong-way risk
If the client fails when markets move against them, losses can exceed contractual protections.
2) Collateral and margin dynamics
Margin models can be procyclical: calm periods lower margin; stress arrives fast.
3) Liquidity and unwind risk
In a crowded trade, liquidation pushes prices, amplifying losses.
4) Operational and legal risk
Documentation, rehypothecation terms, dispute resolution, and settlement failures matter in stress.
Risk controls that actually matter
- conservative margin add-ons for concentrated / illiquid portfolios
- stress testing liquidation horizons (not just VaR)
- concentration limits by strategy and collateral type
- early warning: margin calls, disputes, rapid AUM changes
Sources (starting points)
- Bank prime brokerage disclosures and risk reports
- Market structure primers on margining and securities financing