From Idea to Investment: Building a Bank-Backed Fintech Startup
When startups partner with corporates to launch new ventures, the flashy headlines usually highlight the launch date, the product, and the funding. But what’s often overlooked is the depth of business design and the financial rigor that goes into making such collaborations investable, sustainable, and strategically sound.
While leading the creation of a fintech startup inside one of Portugal’s largest banks, I wasn’t just building a product, I was building a business from the ground up. That meant defining not only the user flows and feature set but the entire business model architecture, validated through data and experimentation.
We started with an intersection of product discovery and business modeling. The initial idea, a financial platform tailored for freelancers, was assessed from both a desirability and feasibility lens. But to get board buy-in, the work had to go deeper.
We built a full business plan with:
- TAM / SAM / SOM modeling: Based on national statistics, market reports, and proprietary user research, we estimated a Total Addressable Market of over 200,000 freelancers. Using segmentation and targeting criteria, we forecasted a Serviceable Obtainable Market of 15% within 3 years.
- Revenue Streams: We modeled multiple monetization paths - subscription fees, interchange fees from card usage, revenue share from integrated accounting tools, and even embedded lending, each validated through user testing and partner negotiations.
Operational and Capital Costs (OPEX & CAPEX): Our plan included detailed projections of product development, compliance, customer acquisition, support, and integration costs, mapped across the product lifecycle. CAPEX included upfront licensing and integrations (e.g., KYC, AML tech), while OPEX factored in growth-stage hiring and support infrastructure. - P&L Simulation: We built a 3-year forecast with quarterly granularity, showing EBITDA, burn rate, break-even point, and a target of €25M NPV. These figures weren’t idealistic—they were grounded in real behavior, unit economics, and acquisition costs, refined through early experiments.
Validation Before Modeling
Our philosophy was simple: never model something you haven’t tested.
Before locking assumptions into Excel, we validated:
- Willingness to Pay (WTP) through pricing interviews and landing page experiments.
- Customer acquisition cost (CAC) with small-scale paid media tests.
- Retention & feature preference via concierge MVPs and usage analytics.
- Where data was missing, we turned to benchmarking and reverse-engineered competitor metrics using startup teardown reports, regulatory filings, and partner input.
We didn’t stop at revenue. We tested cost drivers too, using pilots to understand onboarding time, customer support load, and conversion rates per channel.
When Presenting to the Board/investors, Speak Their Language
For the board and investment committee, we framed the plan not as a startup pitch, but as a strategic business initiative:
- How the venture aligned with the bank’s underserved segments.
- How it could reduce customer churn and expand wallet share.
- What the risks were - and what mitigation plans were in place.
- Why this needed to be a standalone venture vs. an internal feature.
Everything we presented had to feel real and operational, not theoretical. That’s what builds trust.
Corporate venture building isn’t about creating a shiny prototype or a PowerPoint full of buzzwords. It’s about building investable, executable, and scalable businesses that create strategic and financial returns. And that requires doing the hard work up front - understanding the market, validating your financial assumptions, and crafting a business design that holds up under scrutiny.
By Joel Sadio, WSA Youth Ambassador in Portugal.
