Self-Brokerage Isn't an App. It's Everything Underneath It.
Ask a bank what it takes to launch self-brokerage and the first answer is usually "an app".
Ask the team that has tried to build one, and the list gets longer: order execution, custody connectivity, a client ledger, corporate actions, tax, regulatory reporting, onboarding and suitability checks and a front end that clients actually enjoy using.
The app is the part clients see.
Everything else decides whether it works.
Each of those pieces can be bought separately, and that's exactly the problem.
At Slate, we see the same pattern in conversations with banks and fintechs.
Fewer institutions want to assemble execution, custody, front-end, back-office and tax from different vendors.
They want one integrated layer that behaves like a single product, and they want it live in months, not years.
Why buying in silos slows everything down
Every silo you buy is a contract, an integration project, a reconciliation process and a set of failure modes.
The pieces rarely share a data model, so the real cost shows up between them: a corporate action that reaches the broker but not the client's position, a fill that doesn't match the ledger, a tax figure that can't be traced back to the order that created it.
For a classic full-share brokerage product, that complexity is already hard to manage.
Modern self-brokerage makes it harder, because clients now expect to invest an amount, not a number of shares.
What clients ask for, and what it takes to deliver it
A client who wants to put €50 into an ETF, or set up €25 a month into a stock they like, doesn't care that share prices don't divide neatly.
They expect the product to handle it.
Notional trading and savings plans have become the baseline for a modern investing proposition, not a premium feature.
Delivering that experience properly means the infrastructure beneath the app has to do a lot of quiet work:
Aggregated execution. Client orders are netted and sent to the bank's chosen broker in configurable windows, so fractional demand turns into real market orders.
A nominative ledger. Every client's position, down to the fraction, is recorded at client level as a single source of truth.
Corporate actions on fractions. Dividends, splits and other events need to be allocated correctly, and quickly, across every fractional holding.
Tax, per client. Cost-basis methods and local tax reporting have to be calculated on the actual client position, not approximated.
Reconciliation and regulatory reporting. Broker and bank records are matched continuously, and reports such as MiFIR transaction reporting carry the decimal precision that fractions require.
Onboarding and suitability. MiFID II onboarding and appropriateness checks are part of the flow from the first screen.
None of these is exotic on its own.
The difficulty is that they all have to agree with each other, every day.
That is far easier when they come from one coherent layer than when they are stitched together after the fact.
Integrated doesn't mean locked in
There's a fair objection: doesn't one layer mean one more dependency?
It depends on how the layer is built.
Slate is broker- and custodian-agnostic by design.
Execution goes to whichever broker the bank chooses, and settlement runs through the bank's existing custody setup.
The orchestration core sits in between, so a bank can change a broker or custodian later without re-platforming everything above it.
The modules also ship independently, so a bank can start with self-brokerage and grow into other models, such as robo-advisory, on the same foundation, rather than starting again for each new proposition.
That combination of integrated for the bank and flexible underneath is what separates a full solution from a bundle of point products.
Proof that it works at bank scale
When UniCredit Poland set out to launch a new investing app, it did it on Slate.
Across our customers, the pattern holds: launching up to 12 months faster, with up to 80% lower development costs and up to 80% lower operational overhead compared with building in-house or relying on traditional providers.
The speed doesn't come from cutting corners on any single component.
It comes from not having to integrate them one by one.
The question to ask before you start
If you're planning a self-brokerage launch, the most useful question isn't "which app do we build?" or "which vendor do we pick for each piece?"
It's "how many separate integrations are we signing up to maintain, and what happens when one of them changes?"
Want to see what everything underneath the app looks like when it comes as one layer? Book a demo.