It depends on where the bitcoin lands the moment the trade settles. The risk is not the purchase; it is the days or months the holding sits in a trading account afterwards. Decide the custody destination first, then buy through a venue that settles into it, or withdraw in full on settlement. The columns to read are withdrawal controls at the venue and who can move funds at the destination.
Fit engine rules 0.1 (1 Nov 2026), with this situation's inputs preset. Adjust the inputs to your own case. Proof of Custody is published by Onramp Bitcoin, which appears here where its custody model fits and is scored by the same methodology as every other platform.
Recovery: Locate the devices and seed backups, run a signing ceremony with the provider's key; or, where the provider documents an assisted inheritance path, follow that path with the provider.
Recovery: Identity and authority documents to the institutions; no device, seed or ceremony on the heir's side.
Recovery: Locate the quorum of devices and backups, reconstruct the wallet descriptor, sign. Entirely on the recoverer.
Single point of failure at this size: one device, company or person can lose the whole holding.
Recovery: Find the seed phrase, restore it on a compatible device. Fails silently if the seed is lost or the recoverer cannot do this.
These are custody models that fit the situation described, by Proof of Custody's published rules, version 0.1 (1 Nov 2026). They are not a recommendation to buy, sell, move or hold anything, and not legal, tax or estate advice.
A family office holds bitcoin on a trading venue and wants professional custody without adding operational work internally.
The buyer holds more than $10M and needs the arrangement to survive scrutiny from a board, an auditor and an insurer.
Agent tool: fit_custody_setup. Primary sources: poc-scores. Refresh: scores monthly. All routes.
Free, read-only, no key. Every answer carries its source URL, as-of date and the publisher disclosure.