A Guide to Form 1 Schedule A (F1SA) in Prime Brokerage
Updated October 2026. First published June 2024. This version corrects the earlier one, which described the F1SA as the prime broker's agreement with its client.
An F1SA, or Form 1 Schedule A, is the account-level document in a prime brokerage relationship. It ties specific customer accounts to the prime brokerage arrangement that the prime broker and the executing broker documented in their SIA-150. When an order arrives for one of those accounts, the F1SA is how the executing broker knows the trade is a prime brokerage trade and will settle at the prime broker.
Part 3 of our video series, Moving to Self-Clearing, covers the F1SA and the forms around it for a firm that has just started clearing its own trades. It opens on one account that was on track for about 2,500 letters a month. The series page has all four parts, with transcripts.
Moving to Self-Clearing, Part 3: Prime Brokerage Forms. 5:57, captioned.
What an F1SA Is, and What It Isn't
Prime brokerage involves three parties: the customer, the prime broker that carries the account, and the executing brokers the customer trades through. Several documents describe the relationship, and the F1SA is the narrowest of them.
| Document | Between | What it covers |
|---|---|---|
| SIA-150 | Prime broker and executing broker | The base prime brokerage agreement |
| SIA-151 | Customer and the clearing broker on the executing side | The clearance agreement for the customer's prime brokerage trades |
| F1SA (Form 1 Schedule A) | Ties customer accounts to the arrangement | Which accounts the arrangement covers |
| The prime broker's customer agreements | Prime broker and customer | Services, fees, margin lending, and custody |
The earlier version of this post said the F1SA sets out services, fees, margin lending, and custody. Those terms live in the prime broker's own agreements with its customer. The F1SA doesn't replace them, and they don't replace it.
Why the Executing Broker Needs One on File
U.S. prime brokerage still runs on an SEC staff no-action letter from January 25, 1994. When its conditions are met, the executing broker can treat the customer's account as a broker-dealer credit account under Regulation T, and footnote 21 of the letter says a Letter of Free Funds isn't required for trades paid for through the customer's account at the prime broker. The letter doesn't name the SIA forms. They're how the industry documents that its conditions are met, and the F1SA is the piece that connects a particular account to them.
Without a current F1SA, the executing broker can't show that the account is part of a documented relationship. It's left with a customer cash account under 12 CFR 220.8, which means a Letter of Free Funds on every delivery-versus-payment trade to avoid the 90-day freeze. Its other obligations shift with it: it confirms trades directly to the customer, and if the prime broker disaffirms a trade, it treats the customer as its own. What a missing F1SA costs the executing broker walks through a case where one undocumented account was on pace for about 2,500 letters a month.
When an F1SA Goes Out of Date
An F1SA describes accounts as they were when it was signed, so it drifts as the customer's setup changes. The usual causes:
- The customer opens new accounts or restructures existing ones, and trades start flowing before the paperwork catches up.
- The SIA-150 behind it is amended or replaced, and the F1SA still refers to the old agreement.
- A counterparty reorganizes or changes systems, and the documents on file no longer match its account structure.
The order matters. An F1SA only means something against a current SIA-150, so the base agreement has to be in place first. Managing SIA-150, SIA-151, and F1SA documentation covers how firms keep the set aligned.
F1SAs Under T+1
Since May 28, 2024, U.S. trades settle on T+1, and SEC Rule 15c6-2 expects allocations, confirmations, and affirmations on trade date. A prime broker that can't match a trade to a documented account DKs it, and there's no longer a spare day to find the right form. The F1SA needs to be on file before the first trade for an account, not after the first rejection. Reducing DKs from missing prime broker agreements traces how those rejections play out.
How Long to Keep Them
SEC Rule 17a-4(b)(7) requires broker-dealers to keep written agreements relating to their business, including agreements about any account, for at least three years, the first two in an easily accessible place. Because an F1SA governs trades for as long as it's in force, the practical reading is to keep it for its whole life and at least three years after it's superseded.
Loffa's Prime Broker Integrated Network (PBIN) holds F1SAs with the SIA-150 agreements they depend on and the SIA-151 clearance agreements, won't accept an F1SA until the SIA-150 behind it is verified, and keeps PBIN records for the life of the agreement plus six years.