What is prime broker?

A firm that gives large trading clients a single account for financing, custody, and access to many exchanges at once, netting exposure across them instead of requiring collateral at each.

In crypto this solves the capital inefficiency of pre-funding every venue you trade on, and it concentrates counterparty risk in the broker. Failures in the sector have shown what happens when client assets are commingled or re-lent, so how assets are held and whether they are segregated is the question that matters.

Individuals do not use prime brokers, but the term matters to anyone reading about market structure. When commentary says liquidity has thinned or that a fund has been forced to unwind, a prime broker is often the mechanism in between. It is also where the crypto market differs sharply from traditional finance, in which the prime broker and the custodian are usually separate regulated entities.

How it works

Crypto exchanges do not extend credit to each other, so a trading firm operating on eight venues traditionally has to fund all eight in advance. Capital sits idle at seven of them at any moment. A prime broker fixes this by standing in the middle.

1. The client posts collateral once, with the broker.
2. The broker maintains its own funded relationships with each exchange and routes the client's orders there.
3. Positions across venues are netted, so a long on one and a short on another require margin only on the difference.
4. The broker may extend financing against the collateral, which is where leverage and lending enter.

The trade the client is making is capital efficiency in exchange for concentration. Every exchange relationship becomes one relationship, and that one becomes a single point of failure. What protects the client is whether assets are held in segregated accounts at a third-party custodian, or whether they sit on the broker's own balance sheet where they can be lent again. See rehypothecation.

Example

Illustratively, a fund trades on four venues and needs $5,000,000 at each to run its strategy, tying up $20,000,000. Through a prime broker it posts $8,000,000 once and the broker nets its offsetting positions, freeing $12,000,000 for other use.

The saving is real and so is the change in risk. Previously an exchange failure exposed one quarter of the capital. Now a broker failure exposes all of it, and whether the client is a secured creditor or an unsecured one in that event depends entirely on the custody arrangement written into the agreement rather than on the trading terms.

Why it matters when you buy

You will not open a prime brokerage account, but the same question decides where you keep coins: is the asset held for you, or is it a claim against a balance sheet? Retail accounts are almost always the latter. The exchange directory records what each venue publishes about custody and reserves, and protecting yourself from an exchange collapse covers what actually follows from that.

Related terms

rehypothecation — reuse of pledged collateral; segregated accounts — client assets kept apart; custodian — who actually holds the asset; counterparty risk — the exposure being concentrated; otc desk — large trades away from the book; qualified custodian — the regulated custody standard.

Questions

Do retail buyers ever deal with a prime broker?

No. These are institutional relationships with minimums far above individual accounts. The concepts matter because they describe how the market you trade in is financed.

Why did crypto prime brokers fail where traditional ones did not?

Several combined brokerage, custody, and lending in one entity without segregation, so client assets funded the firm's own risk. When those loans went bad the client assets went with them. Separation of roles is the structural difference.

How would I know if my assets are segregated?

Read the terms of service and any published reserve reporting. Segregation is a legal arrangement that has to be stated, and silence usually means the assets are pooled with the platform's own.