How this happens
When an agency onboards a new client for Meta ads, there are two ways to set up the account:
Option A (correct): The client creates their own Business Portfolio, connects their own Facebook Page and Instagram, creates their own ad account — and then invites the agency as a partner with access to those assets. The client owns everything. The agency can access what they need but doesn't own any of it.
Option B (problem): The agency creates the ad account, pixel, and sometimes even the Facebook Page inside their own Business Portfolio. They technically "give" the client access by making them an admin — but the underlying asset is still owned by the agency's portfolio. When the relationship ends, the client is left out. They can't take the ad history, audiences, pixel data, or sometimes even the Page.
Option B is more common than it should be. Agencies sometimes do this out of convenience — it's faster to create everything inside a system they already manage. The client doesn't know the difference until it's too late.
How to check who actually owns your Meta assets
Not your agency's login — your own. If you've never logged into Business Manager or Business Suite with your own account, that's already a sign that you may not have your own portfolio.
What does it say? Is it your business name, or is it your agency's name? If it shows your agency's name, you're inside their portfolio — not your own.
Look at who is listed as the owner of the ad account. If the owner is the agency or an unfamiliar business name — not yours — the account belongs to them.
In Business Settings → Pages, look at the ownership column. A Page "owned" by your portfolio is different from a Page where you've just been given "admin access" through an agency's portfolio.
What your options are if the agency owns your assets
If the relationship is still active: Request in writing that the agency transfer ownership of the ad account, pixel, and Page to your own Business Portfolio. A legitimate agency should have no problem doing this. If they resist or claim it's not possible, that resistance is informative.
If the relationship has already ended: This is harder. If the agency has cut off your access or disappeared, your options are limited to contacting Meta Business Support and documenting that the assets belong to your business — using business registration documents, website ownership, and any contracts you have. Meta can sometimes facilitate transfers but doesn't guarantee them.
Going forward: Any new ad account, pixel, or Page should be created in your own Business Portfolio, with agencies added as partners — never as owners.