Prime Brokerage Anatomy™

Margining: a primer

There is much to say on the topic of prime brokerage margining. Generally,[1] prime brokers have very broad rights to adjust required margin, on short or immediate notice, and to call for more margin, which they can do (at least) daily. You cannot say it loudly enough: margin is a prime broker’s only meaningful defence. If you have enough margin, none of your other protections matter. If you don’t, none of your other protections work.

Margin falls into two categories: margin your broker legally requires you to post — “required margin” — and margin over and above that, that it doesn’t require as such, and which it will return to you if you ask it, but which it is rather pleased you have given it to hold all the same — this is “margin excess”.

Adjusting margin is the process of (re)calculating how much margin you think you’d need, were the world to go to hell overnight and all of Satan’s angels to trample on your Monte Carlo simulations. Having made that calculation, it usually becomes live immediately,[2] meaning you can repurpose any margin excess standing to the credit of your own accounts instantly. If a broker has agreed to “lock up” its margin calculations, it may not be able to convert margin excess to required margin, and therefore will have to give it back.

Calling for margin means demanding that your client pay you some more margin. This you only need to do if there is not enough margin excess to cover the whole of your margin adjustment.

There is no industry standard prime brokerage agreement, so this is not so much an anatomy as a collection of resources about an amorphous subject.
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Margin excess, or “excess margin”, is potential margin: any amount standing to a customer’s account with a prime broker over the minimum margin that the prime broker requires the customer to hold against its liabilities. Margin excess may be in the form of unrealised profit from live transactions, variation margin on swap positions credited to the customer’s account, or excess assets the customer has paid for but holds with the prime broker as custodian.

The prime broker holds or controls it — possession is nine-tenths of the law — but, as long as it stays as “margin excess” — see below — must give it back to the customer on request.

As long as you have a margin excess, you shouldn’t need to make a margin call — a margin adjustment will do.

While the PB holds excess margin it is subject to all the usual security arrangements; the only difference is that the customer is not obliged to let the PB hold it, as such; but customers habitually do, because it is convenient — they have to hold it somewhere, so why not with the good old prime broker? — and because it tends to make their prime brokers feel better about things. And as long as the prime broker has the right to adjust margin at any time, it is justified in feeling quite good about it. If the prime broker must give even a brief notice period before adjusting, then things are quite a bit more fraught.

“As long as it stays as excess margin”

The reality about just when a customer may ask for its excess margin back — “whenever it likes”, in the normal run of things — can startle a complacent risk officer, but what a startled risk officer can then do, should it not terribly like the idea of giving the margin excess back — is to immediately reclassify it as required margin by means of a margin adjustment.

Careful, though: all this, however, is quickly undermined — as those at Credit Suisse in charge of risking The Client Who Shall Not Be Named would tell you, if any of them were left — if there is any notice period before a margin adjustment takes effect, or if there is a margin lock-up.


See also

References

  1. But see the vexed topic of margin lock-up, which significantly constrains the PB’s flexibility.
  2. Archegos had a three day notice period, which interposed some rather gristly squeaky-bum time between your adjustment and it going live, which the Credit Suisse risk team weren’t willing to endure.