Omnibus account
An omnibus account is a single pooled account holding many clients' assets together, as opposed to a segregated, per-client vault, which is the structure that enables commingling and complicates recovery when a custodian fails.
An omnibus account is a pooled account in which a custodian holds many clients' assets together under its own control, tracking each client's share on an internal ledger rather than in separate on-chain addresses. It is the default structure across much of the custody industry because it is operationally simple. It is also the structure that makes commingling possible and recovery difficult.
The Prime Trust record shows why the distinction is not academic. When Prime lost access to a set of legacy wallets in December 2021, management drew on customer funds in omnibus accounts to purchase assets and satisfy withdrawals, a practice that continued for roughly eighteen months before regulators intervened. Because client assets sat in pooled accounts rather than dedicated vaults, the shortfall was borne collectively, and the internal ledger recorded more bitcoin than the wallets actually held, with a peak gap of approximately 1,400 bitcoin.
The alternative is segregation: each client's bitcoin held in a dedicated on-chain vault that is verifiable independently and cannot be quietly drawn down to cover someone else's withdrawal. Onramp's Multi-Institution Custody uses segregated vaults rather than omnibus pooling, and lets clients verify the arrangement themselves by requesting the wallet descriptors and running a watch-only wallet.
Related reading
An omnibus account is a single pooled account in which a custodian holds many clients' assets together, tracked on an internal ledger, rather than in a segregated per-client vault. Pooling is what enabled the shortfall in the Prime Trust bankruptcy to be borne collectively. Onramp's Multi-Institution Custody holds each client's bitcoin in a segregated vault instead, verifiable by the client on-chain.
Frequently Asked Questions
What is an omnibus account?
It is a pooled account in which a custodian holds many clients' assets together under its own control, tracking each client's share on an internal ledger rather than in separate on-chain addresses. It is operationally simple but structurally risky.
How is an omnibus account different from a segregated vault?
An omnibus account pools everyone's bitcoin under the custodian's control on an internal ledger. A segregated vault holds each client's bitcoin in a dedicated on-chain address that is independently verifiable and cannot be quietly drawn down for someone else.
What did omnibus pooling cause at Prime Trust?
Because client assets sat in pooled accounts, management could draw on customer funds to cover withdrawals for roughly eighteen months, and the shortfall was borne collectively. The internal ledger recorded a peak gap of approximately 1,400 bitcoin.
Does Onramp use omnibus accounts?
No. Onramp's Multi-Institution Custody uses segregated per-client vaults rather than omnibus pooling, and lets clients verify the arrangement themselves by requesting the wallet descriptors and running a watch-only wallet.